TU Graz
Graz University of Technology

Advanced Materials Science


Download flyer for Advanced Materials Poster Day 2022

The Field-of-Expertise Advanced Materials Science is an interdisciplinary network of researchers at the TU Graz in chemistry, physics, architecture, mechanical engineering, civil engineering, electrical engineering and geodesy who discover, characterize and model materials, functional coatings and components. The 2022 AMS Poster day will be held in presence on 22.04.

Talks
Lecture Room HS i7, Inffeldgasse 25/D

10:30h 

Welcome and FoE AMS update
Christof Sommitsch, FoE AMS Head

10:50h

FAIR with RDM
Claire Jean-Quartier, Institute of Interactive Systems and Data Science

11:10h

Biopolymers in Biomedical Applications
Karin Stana Kleinschek, Institute of Chemistry and Technology of Biobased Systems

11:30h

Influence of energy distribution on porosity during EBW of thin-walled aluminum components
Matthias Moschinger, Institute of Materials Science, Joining and Forming

12:00h

Poster Session with Buffet

The aim of the poster session is to gather as many contributions as possible from students and postdocs of the AMS FoE and promote an exchange of ideas and networking. When you upload your poster information, please include a link to a one minute video presenting your poster and a link to the poster in pdf format.

 

Posters
9:00 - 18:00 Lecture Room HS i7, Inffeldgasse 25/D


Electron Transfer Reactions of Acylgermanes: A new Synthon for Custom-Made Photoinitiators
Manfred Drusgala, Institute of Inorganic Chemistry

Abstract: Although heavier group 14 acyl-compounds seemed to play a minor role in research for a long time, such derivatives have gained attraction in the last few years, due to their superior properties for light-induced polymerization. Especially tetraacylgermanes stand out due to their high addition rates to the monomer and their high absorption intensities.[1] Additionally, their good photobleaching together with their low toxicity restricts their potential not only to the use for microelectronic, adhesives and inks, but rather predestines them medical application (e.g. for dental fillings). However, a poor solubility in various monomers and a low curing depth still require an improvement.
Therefore, we utilize an innovative pathway which implements the use of strong base- and alkali-metal reduction, to enables a precise finetuning of the PIs properties. Via a single or multiple electron transfer (SET or MET) a highly reactive enolate or bisenolate is formed, which can easily be further derivatized with appropriate electrophiles such as alkyl halides or acid chlorides.[2,3,4] Dependent on the used electrophiles, the PIs properties can be alternated, resulting a custom-made PI, designed to meet the required characteristics for visible-light photopolymerization.

[1] J. Radebner, A. Eibel, M. Leypold, C. Gorsche, L. Schuh, R. Fischer, A. Torvisco, D. Neshchadin, R. Geier, N. Moszner, R. Liska, G. Gescheidt, M. Haas, Angew. Chem. Int. Ed., 2017, 56, 3103.
[2] P. Frühwirt, A. Knoechl, M. Pillinger, S. M. Müller, P. T. Wasdin, R. C. Fischer, J. Radebner, A. Torvisco, N. Moszner, A.-M. Kelterer, T. Griesser, G. Gescheidt, M. Haas, Inorg. Chem. 2020, 39, 2878-2887.
[3] M. Drusgala, M. H. Linden, A. Knoechl, A. Torvisco, R. C. Fischer, H. Bernhard Linden, M. Haas, Eur. J. Inorg. Chem. 2021, 30, 3091–3096.
[4] M. Drusgala, P. Fruehwirt, G. Glotz, K. Hogrefe, A. Torvisco, R. C. Fischer, H. M. R. Wilkening, A.-M. Kelterer, G. Gescheidt, M. Haas, Angew. Chem. Int. Ed. 2021, 60, 23646 –23650


The use of a tertiary solvent mixture to study solvent dynamic effects in the photoinduced electron transfer reaction of excited singlet pyrene and indole
Stephan Landgraf, TU Graz
https://cloud.tugraz.at/index.php/s/sQYeEmAH9G7zCYp

Abstract: Photoinduced electron transfer (PET) plays an important role in many areas of chemistry. The physical properties of the solvent influence the rate constant of PET reactions in many ways. Classical electrodynamical de>>>ion of the solvent reorganization energies in electron-transfer theories use the Pekar factor γ=(1/n2-1/ε) as a solvent parameter. Dielectric constant ε and refractive index n influence the solvent dipole reorientations and contribute to the activation energy of the electron transfer reactions [1]. That is why solvent-dependent measurements of ET reactions start quite early. But, electron-transfer kinetics is also influenced by diffusion and therefore by the solvent viscosity η. Unfortunately, most measurements published use different solvents in a not consequent way [2]. Results of polar and unipolar solvents are compared together with high- and low viscous ones.
We present here the first results of experiments made in a series of solvent mixtures comprising propyl acetate (PA), butyronitrile (BN), and diethyl phthalate (DEP), spanning a wide range of dielectric constants, keeping the refractive index and the viscosity constant [3]. We used the PET reaction of singlet excited pyrene and indole whose solvent dependence is already described in the literature [2]. Quenching rate constants were obtained from Stern-Volmer plots based on both static and dynamic (TCSPC) measurements. Fluorescence lifetimes, quenching rate constants kq, and the ΔG-dependence of ln kq are reported for the solvent mixtures and compared with results reported in pure organic solvents [2].

[1] M. Berghold, J. Bächle, S. Landgraf, G. Grampp, ChemPhysChem, 18,128 (2017).
[2] H. A. Montejano, J.J. Cosa, H.A. Garrera, C.M. Previtali, J. Photochem. Photobiol. A Chem. 86,115 (1995).
[3] A. Wankmüller, M. Berghold, S. Landgraf, J. Mol. Liquids, 333, 115880 (2021).

Smart Core-Shell Nanostructures for Force, Humidity and Temperature Sensing
Taher Abu Ali, Institute of Solid State Physics

Abstract: The work summarized in this abstract presents a multi-stimuli responsive sensor for artificial skin applications. The sensor can detect surrounding changes in temperature, humidity and force. The developed design consists of a hydrogel core, responsive to temperature and humidity changes; and a piezoelectric shell for force sensing. Swelling of the hydrogel core, in response to stimuli, mechanically strains the piezoelectric shell and a measurable electric charge is generated. The two materials are combined into core-shell nanorod structures, using state-of-the-art vapor-based deposition techniques. These deposition techniques provide control over material’s mechanical, optical and electrical properties in addition to film’s conformity and uniformity. Moreover, the core-shell nanorods are deposited into a nanostructured UV-curable resin, providing mechanical stability against structural collapse.


Liquid Phase Deposition of Single-Source Precursors
Aileen Sauermoser, Institute of Inorganic Chemistry

Abstract: Recently, solution processing of silicon based electronic devices has attracted considerable attention. Especially the low costs and the possibility of large area depositions and patterning materials offer great advantage to similar processes. Recent studies demonstrated the principal feasibility of liquid phase deposition (LPD) and processing of silicon films of high quality.[1] Therefore, the aim of this work was the synthesis of different heteroelement substituted higher silicon hydrides, which contain one or more heteroatoms covalently linked to silicon. The resulting materials are then applied as single source precursors for the deposition of functional silicon films. Therefore, different oligomeric compounds were synthesized by UV-activated oligomerization of neopentasilane, 2-methyl-2-silyltrisilane and 1,1,1-trimethyl-2,2-disilyltrisilane.

With the successfully synthesized polysilanes thin layer materials were produced. These thin films were obtained via spin-coating technique on glass substrates under nitrogen atmosphere. Deposition at 500 °C for 60 s was carried out for all materials after spin-coating. By varying parameters like temperature, revolutions per minute, as well as spin-coating time, different series of films were produced and analyzed via light microscopy, SEM and ellipsometry.


[1] a) T. Shimoda, Y. Matsuki, M. Furusawa, T. Aoki, I. Yudasaka, H. Tanaka, H. Iwasawa, D. Wang, M. Miyasaka, Y. Takeuchi, Nature 2006, 440, 783. b.) M. Haas, V. Christopoulos, J. Radebner, M. Holthausen, T. Lainer, L. Schuh, H. Fitzek, G. Kothleitner, A. Torvisco, R. Fischer, O. Wunnicke, H. Stueger, Angew. Chem. 2017, 129, 14259

Flow localization during hot deformation of a Ti-17 alloy
Franz Miller Branco Ferraz

Abstract: Flow localization occurs in titanium alloys during hot deformation. This phenomenon must be avoided to prevent damage and guarantee a correct material flow. In this work, a mesoscale physically-based hot deformation model that couples the microstructure and stress evolution was combined with a phenomenological flow localization model to correlate the thermomechanical history with the microstructure evolution and the susceptibility to flow localization during hot deformation. The onset of flow localization is related to a fast production of new dislocations and new high angle grain boundaries.


Tunable wettability of laser-induced graphene
Alexander Dallinger
https://cloud.tugraz.at/index.php/s/cD8KGimzpR9Pf7W

Abstract: Laser-Induced Graphene (LIG) created by laser scribing on a polymer precursor like polyimide exhibits many interesting properties. Along with creating conductive patterns embedded in flexible substrates the wettability of these materials can be finely tuned by simply changing the IR laser processing parameters. The water contact angle (CA) of LIG could be tuned from a superhydrophilic state -with a CA φ = 0° - to a superhydrophobic state with a CA φ = 150°. Two different strategies were investigated: 1) tuning of the scribing pattern, 2) change of the O2 content of processing atmosphere through local air/N2 purging. The resulting CA of the different LIG types were investigated together with the chemical surface composition, measured by XPS (X-ray Photoelectron Spectroscopy). A correlation between the oxygen content of the surface and the CA could be observed. This opens up the possibility to manipulate and direct fluids on the LIG surface; demonstrators like a fluidic device were fabricated based on these findings. Inspired by the Namib desert beetle a biomimetic application in fog basking was demonstrated. Sheets of polyimide patterned with various types of LIG were used to collect water from fog, with a collection rate similar to other recent but more complicated approaches. An environmental scanning electron microscope (ESEM) was used to investigate the condensation and wetting of water on LIG at the microscale.

Structural evolution of dealloyed nanoporous copper from copper-manganese alloy
Elisabeth Hengge, Institute of Materials Physics, TU Graz

Abstract: Nanoporous electrode materials are highly promising for a broad variety of applications, such as catalysis, sensing, or energy storage due to their high surface-to-volume ratio, free standing porous structure, and freedom of design. The nanoporous structure is obtained by selective etching [1] of the less noble component of an alloy, so called dealloying. The most studied dealloyed materials are noble metals including nanoporous Au, Pt or Pd, but also nanoporous copper (npCu) is known in literature. Because of its low cost, mild fabrication conditions as well as mechanical and electrical properties, npCu is particularly interesting and gained a lot of research interest over the last years. However, the structural evolution is not yet fully understood.
Here, we provide a comprehensive study of the formation of npCu by dealloying a Mn-Cu precursor alloy [2].
Classical electrochemical methods are combined with in situ resistometry [3], revealing that the pore formation is strongly influenced by oxide formation. Complementary scanning electron microscopy (SEM) as well as energy dispersive X-ray spectroscopy (EDS) of the produced np-Cu structures, reveal a hybrid composite of copper and manganese oxide on top of the metallic surface. This unique heterogeneous structure with large surface area could be of major interest for development of electrodes for catalysis and energy storage.


[1] I. McCue, E. Benn, B. Gaskey, J. Erlebacher, Annu. Rev. Mat. Res. 46 (2016) 263
[2] E. Hengge, J. Ihrenberger, E.M. Steyskal, R. Buzolin, M. Luckabauer, C. Sommitsch, R. Würschum, to be published.
[3] E.-M. Steyskal, M. Seidl, M. Graf, R. Würschum, Phys. Chem. Chem. Phys. 19 (2017) 29880

Fatigue assessment of deep rolled components based on numerical analysis
Tobias Pertoll, Institute of Structural Durability and Railway Technology
https://cloud.tugraz.at/index.php/s/6kHpXttR2aJM9xi

Abstract: Weight reduction and associated increasing energy efficiency, enhanced service life and of course reduction of maintenance costs are requirements which are placed on the development of wheelset axles of railway vehicles. A manufacturing process that can contribute to fulfil these requirements is deep rolling. Thereby a deep rolling tool is pressed onto the rotating railway axle with a defined force at a constant feed rate. The surface material layer of the component is smoothed, work-hardened and residual compressive stresses are introduced into the area near the surface. Especially the residual compressive stresses, of course depending on the selection of process parameters, have a positive effect on the service life of the component. Within the framework of this PhD thesis a valid finite element simulation of the deep rolling process will be developed and necessary material investigations for the parametrization and validation will be carried out. Numerical parameter studies to analyse the main process influences, the transferability to real wheelset axles and the consideration of the deep rolling process in the fatigue design are the further main points of the thesis.


Unraveling the timescale of the structural photo-response within oriented Metal-Organic Framework films
Sumea Klokic, Institute of Inorganic Chemistry, Graz University of Technology 8010 Graz, Austria
https://cloud.tugraz.at/index.php/s/soAeXMBB2Mnb5nH

Abstract: Fundamental knowledge on the intrinsic timescale of structural transformations in photo-switchable Metal-Organic Framework films, is crucial to tune their switching performance and to facilitate their applicability as stimuli-responsive materials. In this work, for the first time, an integrated approach to study and quantify the temporal evolution of structural transformations is demonstrated on an epitaxially oriented DMOF-1-on-MOF film system comprising azobenzene in the DMOF-1 pores (DMOF-1/AB). We employed time-resolved Grazing Incidence Wide-Angle X-Ray Scattering measurements (GIWAXS) to track the structural response of the DMOF-1/AB film upon altering the length of the azobenzene molecule by photo-isomerization (trans-to-cis, 343 nm; cis-to-trans, 450 nm). Within seconds, the DMOF-1/AB response occurred fully reversible and over several switching cycles by cooperative photo-switching of the entire oriented film, as confirmed further by infrared measurements. Our work thereby suggests a new avenue to elucidate the timescales and photo-switching characteristics in structur-ally responsive MOF film systems.

Tuning the Porosity of Zinc Oxide Thin Films Derived from Molecular Layer Deposited “Zincones”
Marianne Kräuter, Institute of Solid State Physics
https://cloud.tugraz.at/index.php/s/zWtfE4y5gtwGZJx

Abstract: To establish metal-oxide thin films in crucial fields of application, such as microelectronics or energy conversion, an inexpensive synthesis technique is needed, which excels at scalability and controllability. These requirements are met by chemical vapor deposition methods, which allow for the synthesis of highly conformal layers with precise thickness control and excellent conformality. Additional benefits can be gained by introducing porosity into metal oxide thin films, as this significantly increases the available surface area.
Zinc oxide (ZnO) is a prominent example of a metal-oxide, being a wide-gap semiconductor, which exhibits fascinating properties such as transparency and piezo-electricity.
In this contribution, ZnO is synthesized in a 2-step vapor-deposition process: First, metal-organic “zincone” layers are deposited via molecular layer deposition (MLD). Subsequently, these layers are calcinated to remove their organic contents, thus introducing cavities in the resulting ZnO thin films. The influence of the calcination temperature as well as the influence of the MLD deposition temperature onto the porosity of the ZnO was explored via porosimetric ellipsometry, a technique which has already shown its usefulness for the determination of porosity in polymer-derived oxides.

Phenylene-Bridged Perylene Monoimides as Acceptors for Organic Solar Cells: A Study on the Structure–Property Relationship
Bettina Schweda, Institute for Chemistry and Technology of Materials

Abstract: A series of non-fullerene acceptors based on perylene monoimides coupled in the peri position through phenylene linkers were synthesized via Suzuki-coupling reactions. Various substitution patterns were investigated using density functional theory (DFT) calculations in combination with experimental data to elucidate the geometry and their optical and electrochemical properties. Further investigations of the bulk properties with grazing incidence wide angle X-ray scattering (GIWAXS) gave insight into the stacking behavior of the acceptor thin films. Electrochemical and morphological properties correlate with the photovoltaic performance of devices with the polymeric donor PBDB-T and a maximum efficiency of 3.17 % was reached. The study gives detailed information about structure–property relationships of perylene-linker-perylene compounds.


Microstructure-dependent mesh for crack growth modeling in wheel-rail contacts
Hamed Davoodi, Virtual Vehicle Research GmbH, Inffeldgasse 21a, 8010 Graz, Austria.
https://cloud.tugraz.at/index.php/s/dkRnPxzjKmqT9YS

Abstract: Pearlitic steel is commonly used for wheels and rails in rail transport. This work focuses on the prediction of fatigue crack growth by considering microstructural details of pearlitic steel. Some microstructural properties like prior austenitic grain size, pearlitic colony size, and lamellae orientation as well as the effect of plastic deformation are implemented in the model explicitly by geometrical features of a hierarchical mesh. The meshes generated for this purpose are done based on the Voronoi Tessellation method. The mesh generated with this method shows a strong resemblance to the actual pearlitic microstructure both geometrically and statistically. The mesh can predict anisotropy of fatigue crack growth in different orientations.

Setting up a new dislocation creep model for Ni-based alloy 617
Florian Riedlsperger, Institute of Materials Science, Joining and Forming (IMAT), Graz University of Technology, 8010 Graz, Austria
https://cloud.tugraz.at/index.php/s/yJNbgonSZGBqKiL

Abstract: Alloy 617 is a solid-solution strengthened (SSS), γ‘- and carbide-forming Ni-based alloy. It is a promising candidate for aircraft and power plant applications at 700°C and beyond. In this work, we present a new dislocation creep model for Ni-based alloys with a low γ‘ phase fraction (<10%) and apply it to A617 in a stress range of 165 to 200 MPa at 700°C. The model is capable of predicting creep strain and rupture times based on microstructural evolution, showing good agreement to measurements and literature data.

Material Compatibility Analysis of 316L, AlSi10Mg, AW 6063 and CuAl10Fe5Ni5 for PEM Fuel Cell System Application
Felipe Ralon Rosales, Institute of Materials Science, Joining and Forming (IMAT)
https://cloud.tugraz.at/index.php/s/BP8iQ8eqzaY7jKJ

Abstract: Four different materials, CuAl10Fe5Ni5, AlSi10Mg, AW 6063 and 316L, were investigated upon their compatibility within a proton exchange membrane fuel cell system.
The investigation was performed by applying four different method and four different media, deionised water,
FC-G20 and two sulphuric acid and calcium carbonate mixtures with pH values of 4 and 6 were chosen.
Polarisations curves were created to find corrosion rates for all materials, the AVL material testbed to measure conductivity and temperature in a flowing medium environment for FC-G20 and deionised water, a makeshift setup was created to simulate a low pH value environment for samples with a stirred medium and
leaching tests were performed in all four environments for all fours samples.
The results were assessed quantitatively via inductively coupled plasma-optical emission spectroscopy (ICP-OES) and the Tafel method and qualitatively via visual assessment, conductivity measurement and scanning electron microscopy, respectively to their investigative method.

Fatigue Behavior of Cord Rubber Composite Materials used in Air Spring Bellows
Julian Torggler, Institute of Structural Durability and Railway Technology
https://cloud.tugraz.at/index.php/s/KeNwqWe4gsndWQX

Abstract: In the chassis of a rail vehicle for passenger coaches and traction units, it is common to use air spring systems as secondary spring stages. In the development of spring stages, it is necessary, among other things, to have the most precise knowledge possible about the material properties of the air spring bellows at an early stage of the project. However, with the existing state of knowledge, empirical methods have to be used in most cases.
The damage behavior of fiber composites is special. It is seldom possible to make a statement about the service life of components made of fiber composites. This may lead to time-consuming and costly development with several prototypes necessary.
The aim of this work is to systematically investigate the damage mechanisms evaluated in previous experimental studies on air bellows under laboratory conditions and to analyze the fatigue strength of the base material under different loads.


Design meets Alginate - Synergy of alginate and natural fibres
Hana Vašatko, Lukas Gosch, Julian Jauk, Irena Zivkovic and Milena Stavric, Institut for Architecture and Media
https://www.dropbox.com/s/pe421rzmw91348n/Poster_%20Aginat_TU%20GRAZ_2022.pdf?dl=0

Abstract: The embodied carbon emissions from building materials and construction are today responsible for 38% of annual global GHG emissions in the current global environment. If we are to reach the European energy plan with net-zero emissions by 2050, now is the time to rethink our construction principles, as well as building elements and materials.
One of the possible steps to achieve this goal is to explore new solutions using regional sources and sustainable raw materials. In our research, we use alginate to see if we can substitute conventional building elements with composites based on this sustainable material, whose potential in architecture is so far unrevealed. Alginate, which is found in brown algae cell walls, is an irreversibly hardening elastic moldable material, i.e. once hardened, its form can neither be changed nor converted back into an original state.
Through a five-day workshop, students of material engineering, architecture, design and conservation and restoration had the opportunity to explore the possibilities of using alginate composites as building materials through a series of experiments. Taking into account the tendencies of the natural behaviour of macroalgae (from which alginate is obtained), but also experimenting through the synergy of alginates and different types of natural fibres (cellulose, mineral and protein), elements with the different designs were obtained. The results of the workshop were presented at the Museum of Science and Technology in Belgrade from, February, 25 - 3, March 2022.

In operando monitoring templated electrodeposition of Pt films with hexagonal pore structure by GISAXS
Philipp Aldo Wieser, Institute of Inorganic Chemistry (TU Graz)
https://drive.elettra.eu/f/443203229c06432aa3d2/

Abstract: Liquid crystal (LC) templated electrodeposition is a facile and versatile method to electrodeposit metal films with highly structured mesopores. These mesopores are essential to increase surface area for electrocatalysis and sensing. Previous studies showed that LC templating allowed to tailor pore size, shape, and orientation of the pores in the deposited film. Generally, these studies suggest that the pores in the film inherit the structure of the LC template.
However, little is known about the interplay between the kinetics of the templated deposition, i.e. the transition from the structure of the LC template to the resulting film. A better understanding of this interplay requires in operando monitoring structural changes during the templated electrodeposition process.
As a part of my PhD, we characterized the surface structure of Au substrates during templated electrodeposition of Pt with in operando Grazing Incidence Small Angle X-Ray Scattering (GISAXS).
We were able to identify a series of structural changes at the film surface: A loss of preferential alignment of the LC, followed by the formation of vertically aligned pores. These findings potentially lead to more effective electrodeposition routines and films with higher surface area.

Thermo-responsive shape-memory EPDM/thermoplastic-blends
Reinhold Pommer, Institute for Chemistry and Technology of Materials, Graz University of Technology; Polymer Competence Center Leoben GmbH

Abstract: Shape-memory polymers (SMPs) are a class of smart materials with the ability to recovery from one or more temporary shape deformations into a predetermined configuration upon exposure to external stimuli. Triggers include temperature changes, electricity, light or magnetism. Research on SMPs has been fueled by their potential applications in numerous fields. Within a variety of possible routes, polymer blending is a convenient approach to fabricate material systems exhibiting shape memory behavior.

The present work describes the preparation and investigation of dual- and multi-SMPs based on immiscible blends of ethylene-propylene-diene monomer rubber (EPDM) with different thermoplastics (PE, PP or PP-c-PE). Dynamic mechanical thermal analysis (DMTA), used to characterize the shape memory behavior, shows maximum fixity rates of up to 98% combined with shape recovery rates of 97% in dual-shape cyclization. Results indicate the tunability of thermo-responsiveness and blend morphology by variation of the elastomer/thermoplastic ratio as well as the choice of polymers. Further, triple- and multi-shape features of selected systems were studied.

Zinc oxide ALD growth on different substrates monitored by in-situ ellipsometry
Lisanne Demelius, Institute of Solid State Physics, Graz University of Technology, 8010 Graz
https://cloud.tugraz.at/index.php/s/JRDKjy5ebRrEore

Abstract: Atomic layer deposition (ALD) is a powerful technique to deposit highly conformal thin films with a thickness control in the Angstrom range. The technique is based on a cyclic process during which a precursor gas and a co-reactant are sequentially introduced into the deposition chamber. In our lab, we use oxygen plasma as the co-reactant, which is then commonly referred to as plasma-enhance atomic layer deposition (PE-ALD).
With in-situ spectroscopic ellipsometry, the cyclic ALD growth process can be monitored in detail and important information can be gained about the initial growth and nucleation behavior on different substrates.
Of special interest is the influence of the oxygen plasma on the initial film growth and interface formation. While during PE-ALD on silicon, an immediate growth on-set and a constant growth rate can be observed, on polymer substrates, the presence of the plasma can lead to significant etching. The etching results in an initial decrease of the overall thickness until at some point, ZnO growth takes over and normal linear ALD growth can be observed.
The strength and duration of the polymer etching was found to depend strongly on the chemistry and structure of the polymer substrate.

Wire-based electron beam additive manufacturing of NiTi shape memory alloy: influence of heat treatment on the functional behaviour
Rafael Paiotti M. Guimaraes, Institute for Materials Science, Joining and Forming, Graz University of Technology

Abstract: The fabrication of Shape Memory Alloys (SMA) by wire-based electron beam additive manufacturing (w-EBAM) has started only recently. In previous studies, solidification aspects, comparison with other directed energy deposition techniques, and crystallographic aspects of the deposition along the building direction were clarified. Despite all the aforementioned cases that have assessed the manufactured material mechanically, one has to highlight the fact that the influence of thermal treatments on the functional behaviour is still scarce. Moreover, it is well known the influence of the precipitation caused by such treatments on the improvement of the superelastic effect, especially the coherent Ni4Ti3 particles. In this sense, it is fundamental to understand how w-EBAM fabrication may impact this metallurgical phenomenon as well as the mechanical behaviour. Therefore, the present work aims to shed light on the metallurgical behaviour of SMA fabricated by w-EBAM, investigating the functional properties and correlating their responses to thermal treatment time and temperature.


Transport of organic volatiles through paper: physics-informed neural networks for solving inverse and forward problems
Alexandra Serebrennikova, Institite of Solid State Physics
https://cloud.tugraz.at/index.php/s/sqg6LnSnDRWyrxp

Abstract: Transport of volatile organic compounds (VOCs) through porous media with active surfaces takes place in many important applications, such as in cellulose-based materials for packaging. Generally, it is a complex process that combines diffusion with sorption at any time. To date, the data needed to use and validate the mathematical models proposed in literature to describe the mentioned processes are scarce and have not been systematically compiled.

As an extension of the model of Ramarao, 2003 [1] for the water vapour transport through paper, we propose to describe the transport of VOCs by a non-linear Fisher-Kolmogorov-Petrovsky-Piskunov equation coupled to a partial differential equation (PDE) for the sorption process. The proposed PDE system contains specific material parameters such as diffusion coefficients, adsorption rates etc. as multiplication factors.

Although these parameters are essential for solving the PDEs at a given time scale, not all of the required parameters can be directly deduced from experiments, particularly diffusion coefficients and sorption constants.

Therefore, we propose to use experimental concentration data, obtained for the migration of dimethyl sulfoxide (DMSO) through a stack of paper sheets, to infer the sorption constant. These concentrations are considered as the outcome of a model prediction and are inserted into an inverse boundary problem. We employ Physics-Informed Neural Networks (PINNs) to find the underlying sorption constant of DMSO on paper from this inverse problem.

We illustrate how to practically combine PINN-based calculations with experimental data to obtain trustworthy transport-related material parameters. Finally we verify the obtained parameter by solving the forward migration problem via PINNs and finite element methods on the relevant time scale and show the satisfactory correspondence between the simulation and experimental results.

[1] Ramarao BV, Massoquete A, Lavrykov S, et al (2003) Moisture Diffusion Inside Paper Materials in the Hygroscopic Range and Characteristics of Diffusivity Parameters. Drying Technology 21(10):2007–2056. https://doi.org/10.1081/DRT-120027044

On the printability and superelasticity of NiTi shape memory alloy by selective laser melting with Ni-rich elementally blended powder
Eva Graf, Institute of Materials Science, Joining and Forming (IMAT), Graz University of Technology

Abstract: The fabrication of NiTi shape memory alloy by laser powder bed fusion has gained much interest since NiTi shows a lack of machinability in terms of conventional routes. Previous studies successfully produced dense and defect-less NiTi with pre-alloyed powder; typically produced on a prior heated NiTi substrate plate. However, these pre-alloyed NiTi powders are costly and difficult to produce due to their reactivity, becoming a drawback thus hindering NiTi application. For this reason, the achievement would be to produce high-quality parts by using elementally blended Ni and Ti powder printed on a dissimilar material substrate plate – such as titanium –, as a cost-effective alternative. Furthermore, the elementally blended powder gives freedom in varying chemical composition of the NiTi alloy since pre-alloyed powders have a fixed narrow composition range. It is well known that the chemical composition of NiTi alloys influences mechanical behaviour such as the shape memory effect (SME) and superelasticity (SE). Therefore, the present work is focused on a process parameter study to correlate machine-related parameters with the printability and defects in the material additionally investigating its superelastic response.


INJECTION OVERMOULDED POLYMER-METAL HYBRID STRUCTURES
Gean Marcatto, Graz University of Technology (TU Graz), Graz, Austria; Federal University of Sao Carlos (UFSCar), São Carlos, SP, Brazil

Abstract: Polymer-metal hybrid (PMH) structures are specially designed and manufactured to bring together the relevant characteristics of each component into a single structure. In this sense, these structures can combine the mechanical strength of metals with the lightness and durability of polymers. They are used in various sectors such as transportation, household appliances, energy and biomedical. Metal insert injection over-molding is an important technique for assembling polymer-metal hybrid structures. It is based on the injection molding of thermoplastics, an automated process that makes it possible to obtain parts with complex geometries and dimensional precision in very short molding cycles. In this context, hybrid structures of polycarbonate (PC) and aluminum alloy AA6061 were obtained by direct-adhesion injection over-molding. The surface of the AA6061 substrate was structured by laser under different conditions. The effects of laser speed and frequency on the depth of grooves drawn on the surface of the aluminum substrate were evaluated and a correlation with the lap-shear strength of half-lap splice PC/AA6061 joints was obtained. A strong joint with maximum lap shear strength of 6.2  0.3 MPa was reached.


Modelling the hot deformation of a microalloyed steel
Saham Sadat Sharifi, Institute of Materials Science, Joining and Forming (IMAT), Graz University of Technology, 8010 Graz, Austria
https://cloud.tugraz.at/index.php/s/KcwZxMPyqqtGScB

Abstract: During the continuous casting process, alloys are exposed to mechanical and thermal stresses which might lead to damage. The strain hardening effect and dynamic softening behavior of a microalloyed steel are correlated to the damage behavior occurring during hot deformation.
The use of physically-based models in modeling thermomechanical processes allows for a better understanding of the mechanisms responsible for the material properties. They are a powerful tool to improve industrial processes. In this work, a model featuring dislocation density as an internal variable was developed to capture the work-hardening and dynamic softening of a microalloyed steel at processing conditions. In the Austenitic range, dynamic recrystallization model is implemented, and the damage behavior is modeled by considering the effects of the microstructure evolution and the DRX fraction. The model is then developed for microstructure containing two phases using Iso-work law, which considers the softening mechanism of both austenite as low SFE material and ferrite. The phase transformation model was as well implemented.

Studies of Ionizing Radiation Effects in Nano-Scale CMOS (SIRENS)
Martin Apro, Semih Ramazanoglu, Alicja Michalowska-Forsyth, Institute of Electronics, Graz University of Technology, 8010 Graz
https://cloud.tugraz.at/index.php/s/mpTSL9ZAn9Ys62S

Abstract: High energy physics experiments are creating an increasing demand for integrated circuits (ICs) that can reliably work at higher frequencies, with smaller signal levels and under the influence of large doses of high energy radiation. A leading example of this trend is the next upgrade of large hadron collider (LHC) at Conseil Européen pour la Recherche Nucléaire (CERN). The integrated circuit technologies used in applications with high energy radiation environment have to be carefully selected and characterized both at single transistor and circuit level. The focus of this project is to examine total ionizing dose (TID) influence on 28 nm and 40 nm CMOS "high-dielectric-constant-metal-gate" (high-K) technology nodes and establish reliable models for DC, 1/f noise and Random Telegraph Noise (RTN) behavior under different operating conditions.


In-situ alignment of dielectric fibers with electric fields in extrusion processes
Florian Lackner, Rupert Kargl, Karin Stana-Kleinschek, Institute of Chemistry and Technology of Biobased Systems, Graz University of Technology, Austria
https://cloud.tugraz.at/index.php/s/5B7M6x7ZoJ5BdwP

Abstract: Biological systems found in nature exhibit highly complex hierarchically ordered 3D structures with many degrees of organization and functionalization to achieve their unique mechanical and biological properties. While biological systems grow theses anisotropic reinforcement architectures, the fiber alignment in polymer processing and especially 3D printing requires external forces such as shear force, electric – or magnetic fields and is often limited to specific scenarios.[1]
Herein, the research results for a nanofiber alignment technology transferable to extrusion-based 3D printing employing electrical fields is reported. Using optical microscopy and a specially designed flow cell, we were able to measure and visualize the competition between the alignment due to uniaxial shear forces and the alignment due to the imposed electric field perpendicular to the flow direction. With this proof-of-concept study a European patent application was filed. [2]


[1] Y. Yang, Z. Chen, X. Song, Z. Zhang, J. Zhang, K. K. Shung, Q. Zhou, Y. Chen, Adv. Mater. 2017, 29, 1605750.
[2] "Alignment of dielectric fibers" , European Patent Office, Ref. No. E_0991, submitted Feb. 2022

Computer-aided topology optimization of through-the-thickness reinforcements for metal-composite hybrid joints produced via U-Joining
Talina Terrazas Monje, Graz University of Technology – TU Graz, Institute of Materials Science, Joining and Forming, BMK Endowed Professorship for Aviation, Kopernikusgasse 24/1, 8010
https://cloud.tugraz.at/index.php/s/NiMDmyLzPoxA7GD

Abstract: This work presents an alternative for the topology optimization of the through-the-thickness reinforcements (TTRs) used for Ultrasonic Joining (U-Joining) of hybrid structures in lap-shear configuration. Hybrid joints were considered between stainless steel 316L and 20% short-carbon-fiber reinforced polyether-ether-ketone (PEEK-20CF). For the optimization, a finite element (FE) model was developed in Abaqus and implemented into an optimization workflow in ISight. Metallic samples featuring the optimized geometry were manufactured using laser powder bed fusion (LPBF), joined using U-Joining with a polymeric counterpart printed via fused filament fabrication (FFF), and tested. The obtained optimum geometry can reach a maximum force of 2940.0 N during loading (34% higher than standard TTRs) based on the simulation outcomes. With such geometry, full penetration into the polymer and total wetting of the metal surface was achieved during U-joining, demonstrating its overall suitability for this technique. Moreover, the lap-shear mechanical testing results indicated that the average maximum force that the optimized TTRs can reach is 2746.3 N, which showed good agreement with the simulation results.

Optimization of metal-polymer hybrid joints fully produced by Additive Manufacturing using Decision Tree Algorithm
Carlos Belei, Graz University of Technology, Institute of Material Science, Joining and Forming – BMK Endowed Professorship for Aviation, 8010 Graz, Austria

Abstract: The advantages provided by Additive Manufacturing (AM) techniques for both metals and polymers with respect to possible part geometries and reduction of manufacturing steps are well known. However, coupling different AM techniques to produce polymer-metal hybrid is yet to be thoroughly explored. While conventional joining technologies such as fastening and adhesive bonding would be capable of joining polymer and metal AM parts, this work aims towards using AM itself as a joining technology for that. Known as AddJoining, this approach resorts to Fused-Filament Fabrication (FFF) principles to manufacture parts directly onto metallic substrates, dispensing any kind of joining step, fasteners or bolts. Since the AddJoining relies on the hot, softened extruded polymer flowing through surface irregularities, using a substrate with an appropriate roughness is important. In a scenario where the substrate has been produced by powder-based AM techniques, its as-printed surface (which normally would need to be milled out for most applications) can be utilized to provide anchoring spots for the semi-liquid extruded polymer. The objective of this work is to evaluate the influence of the as-printed surface roughness, as well of subsequent FFF parameters on the strength of Ti-6Al-4V/PA-CF joints produced by AddJoining. In order to test the joints, a 3-point bending method based on ISO 14679:1997 standard was deployed. The roughness was varied by 3D-printing the substrate with different leaning angles (from 40 to 90 degrees). As for the polymer part, layer height and printing speed of the coating layer (the polymer layer immediately in contact with the metal) were also varied. The influence of the aforementioned parameters on the bending force was interpreted using single Decision Tree Regression, as well as Ensemble methods combining several trees to produce better predictive performance (e.g. Random Forests, Adaboost, Bagging, etc.). Random Forests was deemed to be the most promising model, to which further hyperparameter tuning was conducted. As a result, a coefficient of determination (R2) of 0.97 was obtained for both training and test sets . The model clearly suggests that printing speed is the prominent parameter followed by leaning angle. Additionally, the combined effect of low printing speed and leaning angle yield the highest bending force. This result is agreement with experimental trials.

PRODUCTION OF BORON-MODIFIED STAINLESS-STEEL POWDERS FOR LASER POWDER BED FUSION
Brenda Juliet Martins Freitas, Institute of Materials Science, Joining and Forming, BMK endowed Professorship for Aviation, Graz University of Technology (TU Graz), Graz, Austria

Abstract: Metallic components employed in harsh applications in the oil & gas, marine, and chemical industries are subjected to surface degradation such as wear and corrosion. Stainless steel alloys are corrosion-resistant, but not considered as significantly wear-resistant. Addition of high boron contents (0.3–4 wt.%) has demonstrated to be effective to enhance the hardness and wear resistance of stainless steels due to the formation of hard and rigid borides. However, due to low machinability of these alloys, the manufacture of components with complex geometries is difficult. Hence, laser powder bed fusion (L-PBF) process is an interesting additive manufacturing route for boron-modified stainless steels, since it is possible to produce near-net-shape components with a variety of dimensions and geometries. Moreover the process offers the possibility to control printed part’s microstructure by adjusting the processing parameters, with reduced waste of material, and the possibility to produce and/or repair specific components in a short time. This study reports the production of boron-modified stainless-steel powders by gas atomization focusing on its application in the production of parts by L-PBF. Current studies at TU Graz are addressing the L-BPF-parameters optimization, and the systematic analyzes of the microstructure, mechanical, wear and corrosion resistance of the printed parts.

The effect of an in-situ consolidation process on the microstructure of additive manufactured continuous carbon fiber reinforced polyamide 6 material.
Hannes Oberlercher, Institute of Material Science, Joining and Forming, BMK Endowed Professorship for Aviation
https://fhkarnten-my.sharepoint.com/:b:/g/personal/oberlercher_fh-kaernten_at/EdkZiBSNf3dEm4YoyqwikssB1mdOWm7Lxa-VQIqtl8jjzw?e=cdA6JT

Abstract: The additive manufacturing (AM) of continuous fiber reinforced composites (CFC) is becoming increasingly important in the field of lightweight construction. The major advantage lies particular in the automated manufacturing process and in the production of complex geometries. Recent works on AM CFCs printed by traditional fusion filament fabrication (FFF) have revealed increased consolidation-related volumetric flaws -i.e. deconsolidation defects decreasing mechanical performance. The presence of deconsolidation defects, normally indicates either poor process parameters selection or inadequate in situ consolidation. This work is an intrinsic characteristic of traditional FFF, where there is no application of additional in situ consolidation pressure. Recently, there were several efforts in modifying the FFF of CFCs to minimize deconsolidation defects through in situ thermo-mechanical pressing. However, there are only limited fundamental knowledge on the in situ thermo-mechanical consolidation of FFF-CFCs. This work analyses the stated problem and proposes ways to decrease deconsolidation in FFF CF-PA6 laminates. For this purpose we used a self-developed FFF printing head coupled with a thermo-mechanical pressing unit. The influence of extrusion-, consolidation temperature, printing speed and in situ consolidation pressure on laminate microstructure and flexural strength was investigated. A comparison with FFF laminates printed in a common 3D printer was performed.

Azacryptand-based Dinuclear Rare-Earth Metal Compounds: A Platform for Cooperative Chemistry
Johanna Uher, Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria

Abstract: Rare-earth metals are essential in numerous technological applications due to their magnetic and photophysical properties. Playing key roles in electric vehicle motors and wind turbines, an average smartphone for instance contains around eight different rare-earth metals with applications in color displays, touch screens, vibration motors, and speakers. On the level of coordination chemistry rare-earth metal are on the forefront of small molecule activation such as dinitrogen and carbon oxides. Activation of these gases, which are key in the in the production of chemical products like fertilizers and synthetic hydrocarbons, is typically accomplished by two rare-earth metal centers working together.
Here, we would like to present our initial work on dinuclear rare-earth metal azacryptand compounds. Azacryptand cages provide an ideal environment to bind two rare-earth metal ions and at the same time enable cooperative interaction between these ions to engage in small molecule activation. As part of our research, we explored disamarium and dilanthanum compounds and demonstrated their ability to bind molecules such as cyanide, which is isoelectronic to dinitrogen and carbon monoxide, and borohydride, which is a potent reducing agent for carbon oxide moieties.


Investigation on the optoelectronic properties and photo-degradation of PM6:Y6 organic solar cells and their correlation to the device architecture
Elena Zuccalà, Institute for Chemistry and Technology of Materials

Abstract: PM6:Y6 based solar cells have emerged as some of the best performing organic solar cells in the last five years: not only their power conversion efficiencies (PCEs) are among the highest performances reported so far[1], but, under optimized fabrication conditions, PM6:Y6 blends have also shown outstanding photo- and storage stability.[2]
Still, recent studies have hardly accounted for the correlation between the modification of the device structure and its effects on the solar cell degradation under continuous illumination in operating conditions.
Here, we focus on the influence of the device architecture on PM6:Y6 solar cells by examining the conventional and inverted structure, in combination with the processing of the photoactive blend with and without the additive chloronaphthalene. For each configuration, we investigated the electronic properties, maximum power point (MPP) tracking, as well as the absorber layer morphology.
We observed that conventional solar cells led to PCEs of approximately 14.5%, showing that their performance was not significantly affected by the presence of the additive. After 16 hours under continuous illumination and MPP tracking, 95% and 92% of the initial PCEs were retained in the devices with and without additive, respectively. On the contrary, the solar cells with inverted structure reached PCEs of 12% with and 13% without additive. However, the PCE aging curves collected by MPP tracking displayed a similar decreasing behavior, dropping below 90 % of their initial values in both cases. Further analyses revealed that a change in the crystallinity of Y6 and its interaction with the interlayers could be responsible for the different degradation trends.
These results contribute to a better understanding of the aging mechanisms of PM6:Y6 solar cells, which will lead to improved electronic characteristics and longer device lifetimes.



[1] Z. C. Wen, H. Yin, X. T. Hao, Surf. Interfaces 2021, 23, 100921.
[2] Y. Han, H. Dong, et al., ACS Appl. Mater. Interfaces 2021, 13, 17869−17881.

Preparation of honeycomb-structured metal sulfide thin films via polystyrene microsphere templates
Thomas Rath, Institute for Chemistry and Technology of Materials, NAWI Graz, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
https://cloud.tugraz.at/index.php/s/YqciTnAyRfzPaLp/download

Abstract: Metal sulfides currently experience increased interest due to their well-suited properties for a broad area of applications such as photovoltaics, photocatalysis, or energy storage. In literature, there are many reports for the synthesis, characterization and application of metal sulfide films, but only a few deal with structured metal sulfide films. Most of the routes towards structured metal sulfides employ templates. There are two main template-assisted methods, the soft-templating with directing agents, such as lyotropic liquid crystalline templates, and the hard-templating with templates such as mesoporous silica. Nanosphere colloidal lithography is a technique that is classified in the soft-templating technique and utilizes monodispersed colloidal particles, such as polystyrene microspheres (PS-MS), as template for the formation of periodically ordered arrays.
In this poster, a novel synthesis method for honeycombed-structured metal sulfide thin films via a nanosphere colloidal lithography technique is presented. The process consists of three steps, the PS-MS template formation, the metal sulfide precursor infiltration followed by the conversion to the metal sulfide and finally, the template removal. The properties and features of the films are studied via several techniques such as profilometry, FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy.


A micromechanical model of cellulosic foams – validation and results of first parametric studies
Markus Wagner, Georg Baumann, Florian Feist, Vehicle Safety Insitute - Crashworthy Biobased Composites

Abstract: Cellulosic network structures are a potential sustainable and ecological alternative to current synthetic foams. The EU funded project ‘BreadCell’ explores porous cellulosic structures generated through a biological foaming process employing yeasts.
The development of the material and the process is assisted through structural micro-mechanical model of the structure, which is influenced by numerous parameters – related to the fibre (length, cross-section, kinks, curls, fibrillation, strength and stiffness) and the morphology of the network (pore size, relative pore volume).
A tool was developed that automatically generates a micromechanical model representative of the fibrous structure for a given set of fibre and foam parameters. The generator returns a runnable input deck of the bulky or planar fibrous network structures.
The numerical model was validated against data from experimental tests of planar and bulky cellulosic network structures. A first parametric study was conducted, showing that fibrillation and directionality are key parameters to increase stiffness and strength of the foam. As an outlook approaches that will improve the model’s fidelity are identified.

Corrosion resistance of cast AlSi10MgCu(x) alloys
Marlene Eichlseder

Abstract: Aluminium has a high strength-to-weight ration making it an attractive alloy for automotive industry. Among the aluminium alloys, cast Al-Si-Mg are typically used in near net-to-shape components, such as engines and motors. Currently, recyclability is of great importance. Although aluminium can be easily recycled, contamination intake can occur. The typical ones are iron, manganese and copper. Copper is typically added in aluminium alloys to increase the strength but it decreases the corrosion resistance. In this work the effect of the added copper on the corrosion resistance is examined on AlSi10Mg alloys with different copper concentrations. Salt spray measurements were conducted to determine the corrosion rate and electrochemical tests were performed to investigate the corrosion behaviour. With linear polarization measurements the corrosion current was examined while impedance measurements were conducted to simulate and better understand the aluminium dissolution process. Finally, the effect of copper on the corrosion degradation of the AlSi10Mg alloys is determined.


The Characterisation of Materials at High Strain Rates with a Universal Split Hopkinson Bar System
Georg Baumann, Florian Feist, Vehicle Safety Insitute - Crashworthy Biobased Composites

Abstract: The mechanical response of most materials is significantly influenced by the applied loading-rate. Knowlegde on the strain-rate dependency of strength- and stiffness-values as well as on damage accumulation is relevant for a mulititude of engineering problems, like metal forming, vehicle crash safety, or bird strike impact tolerance on airplanes.

In order to characterize the dynamic mechanical response of materials under high strain rates one typical test-setup ist the Split Hopkinson Bar. It is basically a system of long and slender bars and uses the principal of one-dimensional shock wave propagation. This allows for strain-rates between roughly 100/s and 10 000/s. Many of these test benches are designed in such a way that they can either be used for compressive or tensile loading. The system installed at the Vehicle Safety Institute can be universally used for tensile or compressive loading.
In addition to the actual strain-gauge-based measurements, high speed images of the specimen are taken during the test. Based on these images, the local strain distribution can be determined using DIC (Digital Image Correlation).
The system is further equipped with a temperature chamber.
The poster examplarily shows the comprehensive characterisation of relatively soft and anistropic materials like solid wood but also of foams and metals as well as fibre-reinforced plastics. Furthermore, it can be used for validation-experiments, as demonstrated by the impingement loading experiments of high-voltage bus bar insulations.
The poster concludes with typical mechanical responses of materials at elevated strain-rates.


Solvent-Free Amide Bond Formation using a variety of Methoxysilanes as Coupling Agent
Thomas Lainer, Institute of Inorganic Chemistry

Abstract: Amide bond formation is one of the cornerstones of organic chemistry. Amide bonds are found in a variety of products like pharmaceuticals and polymers. About 25% of all pharmaceuticals currently contain an amide bond. Due to this the investigation of alternative coupling reagents is an important task in contemporary chemistry. In this context silane-mediated coupling has become popular over the past few years, owing their low toxicity and good availability. We investigated the reaction of different carboxylic acids with primary and secondary amines with tetramethyoxysilane 1, hexamethoxydisilane 2 and dodecamethoxyneopentasilane 3 as coupling agent (Scheme 1). Moreover, we implimented that the reaction can be performed solvent free and without exclusion of air and moisture.

Additive manufacturing of an Fe-Cr-Co permanent magnet alloy with a novel approach of in-situ alloying
Siegfried Arneitz , IMAT
https://web.tresorit.com/l/6ZXA6#EzjA0MjmYuRVMItJyPr-vQ

Abstract: In recent years, the method of additive manufacturing has become more and more important in the production of magnetic materials due to higher demands for miniaturisation and complex- shaped magnet parts. With the method of Laser beam- powder bed fusion (LB-PBF), an in- situ alloying process for the additive manufacturing of the Fe-Cr-Co system has been developed. With this novel method the production of complex alloys with a composition accustomed to each specific case of application can be achieved directly in the printing chamber by the use of elemental powders or simpler commercial alloy powders as base materials.
In this work, homogeneity of the element distribution in the as- printed samples, which has shown to be of crucial importance for the development of good magnetic properties has been examined by EDS measurements. The influence of the printing parameters on the element distribution has been studied thereby. For these alloys, the magnetic properties of samples with different parameters and after different heat treatments has been studied and the microstructure has been characterised by SEM/ EBSD investigations. The shape and the composition of the spinodal phases developed under these different conditions has been examined via TEM investigations

High entropy alloys produced by laser powder bed fusion assisted by in-situ alloying
Ricardo Henrique Buzolin, Institue of Materials Science, Joining and Forming

Abstract: High-entropy alloys (HEAs) are materials of interest due to their excellent mechanical properties such as high strength and high ductility under both cryogenic- and high-temperature conditions. Currently, their production on an industrial scale is still being established. Innovative manufacturing techniques can facilitate the production of HEA structural parts. Additive manufacturing combined with in-situ alloying enables the production of complex alloys using high-quality powders of pure individual elements or pre-alloyed powders. Laser Powder Bed Fusion enables the production of complex shapes with internal closed fine features, which are not feasible via any other state-of-the-art metal formative or subtractive process. With this technique, various adjustable process conditions are possible due to the wide range of possible printing parameters. In this work, high entropy alloys are produced using laser powder bed fusion assisted by in-situ alloying. The microstructure is characterised and correlated to the main printing parameters. Moreover, the relations between crystallographic textures and printing parameters are inferred. The partial powder melting inherent from the in-situ alloying method and the micro-segregation due to laser powder bed fusion are successfully minimised with solution heat treatments.

Wire-Based Additive Manufacturing of Tungsten
Florian Pixner, Institute of Materials Science, Joining and Forming
https://cloud.tugraz.at/index.php/s/2cXoYfNty6LciLP

Abstract: In present study, the feasibility of wire-based additive manufacturing of commercially pure tungsten using electron beam technique could be demonstrated. Three different representative volumetric AM structures were built and subsequently characterized. The parts show a sound visual appearance with the absence of (macroscopic-) cracks or severe distortion. The fabricated parts exhibit high density and the value depends on the welding sequence applied. The mean hardness value of the fabricated AM structures is about 366 - 380 HV1 and is in the range of about 89 - 93% of the conventionally fabricated substrate. Microstructural changes for all AM structures could be observed; a coarsening of the grains from the bottom to the top and a change in morphology can be noted for all AM structures.


Physical upset butt welding simulation for high performance Q&T steels
Sebastian Fritsche, Institute of Materials Science, Joining and Forming, Graz University of Technology

Abstract: High-performance Q&T steels are widely used for steel chains and therefore the chain joining process has to be taken into account in an early stage of development of new steel grades. To guarantee high availability and cost efficiency, a scheme for the physical welding simulation of the upset butt welding process was elaborated within this study by applying it to the Q&T steel 23MnNiCrMo5-2. By conducting thermo-mechanical simulations on the Gleeble® 3800 (Dynamic Systems Inc.) the influence of different process parameters on the joint performance could be determined. Furthermore, feasibility was shown for simulating the weld zone by conducting upset butt welding under controlled ambient influences by the use of the stated Gleeble® simulator. By establishing a suitable welding procedure with appropriate control parameters, high-quality joints with geometrical features and microstructure, comparable to the industrial welding process, could be observed.

Ultrasonic joining parameters optimization and surface corrosion behavior of additively manufactured 316L and PEEK-20CF hybrid structures
Willian S. de Carvalho, Graz University of Technology – TU Graz, Institute of Materials Science, Joining and Forming, BMK Endowed Professorship for Aviation, Kopernikusgasse 24/1, 8010

Abstract: Ultrasonic Joining (U-Joining) is a novel friction-based joining technique capable of producing through-the-thickness reinforced (TTRs) hybrid joints between surface-structured metals and unreinforced/fiber-reinforced thermoplastics. The process feasibility has been successfully demonstrated and optimized to join injection-molded Ti-4Al-6V and extruded unreinforced and glass-fiber-reinforced polyetherimide parts, resulting in joints with improved quasi-static out-of-plane mechanical properties. In addition, a previous study explored the joining process of additively manufactured 316L stainless steel with 20% short-carbon-fiber reinforced poly-ether-ether-ketone (PEEK-20CF). However, further investigation of joining process parameters’ effect on joint mechanical performance is needed to understand joint formation and strength. This work intends to evaluate the influence of U-Joining parameters on the mechanical performance and surface corrosion behavior of laser powder bed fusion (LPBF) printed 316L stainless steel and fused filament fabricated (FFF) PEEK-20CF hybrid single-lap joints. The joining parameters were optimized through Design of Experiments (DoE) to maximize the single-lap joint ultimate lap shear force (ULSF). Furthermore, the corrosion behavior of optimized joints was analyzed via potentiodynamic polarization techniques performed in simulated seawater saline corrosion medium (3.5 wt.% NaCl). The obtained results showed that the mechanical performance of the produced joints strongly depends on the joining energy and pressure. In addition, a similar corrosion behavior was observed between the as-built base material and optimized joined hybrid parts, indicating that U-Joining is suitable for transportation applications since it is not detrimental to the corrosion resistance of the investigated materials.


Dissimilar joints of additive manufactured and wrought aluminium alloy produced by refill friction stir spot welding
Sebastian Fritsche, Institute of Materials Science, Joining and Forming, BMK endowed Professorship for Aviation, Graz University of Technology

Abstract: With refill friction stir spot welding (RFSSW) solid-state joining of aluminium alloys, not weldable with fusion-based processes, is possible. Hence the process is used in this study to join AlSi10Mg, processed by laser powder bed fusion (LPBF), with high-strength wrought alloy AA7075-T6. Rotational speed was varied to investigate different heat inputs at constant plunge depth and welding time. The investigation showed the best mechanical properties and integrity for medium heat input joints, where the best balance between hook height and integrity was observed. The feasibility of RFSSW for joining AlSi10Mg with high strength wrought alloys was confirmed showing high potential for further investigations and industrial applications.