The current study aims to increase the deposition rate of Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242) wire using cold metal transfer welding in wire-arc directed energy deposition (waDED). A deposition rate of 1.8 kg/h was achieved, surpassing the current state of the art, similar to 0.6 kg/h, for Ti-6242 in waDED. Microstructural characterization revealed a fine alpha+beta microstructure within columnar prior-beta grains, averaging similar to 500 mu m. The alpha-phase shows lamellar morphology. Tensile testing was conducted at three distinct temperatures. At room temperature a tensile strength of 1020 MPa and an elongation at fracture of 7.3% was reported. Increasing temperatures to 300 and 550 degrees C led to a decrease in ultimate strength and an increase in ductility. Creep testing was conducted at 550 degrees C, 575 degrees C and 600 degrees C, at a constant load of 210 MPa. Minimum creep rates achieved were below 1 x 10(-7)s(-1). The calculated activation energy was 380 kJ/mol. Based on this value; the active creep mechanism was inferred to be dislocation climb assisted by diffusion. Mechanically, the deposited material did not present any critical defects or early failures and achieved equivalent or superior properties to wrought and other additively manufactured Ti-6242. However, some anisotropic features were identified throughout mechanical testing. The results obtained in this study confirm that the conventional alloy Ti-6242 can be processed by waDED at high deposition rates and achieve reproducible properties, enabling cost and environmental savings for high-temperature aerospace or stationary turbine applications.

This study explores a repeated creep indentation approach to investigate the underlying deformation mechanisms in metals by extracting key deformation activation parameters. Using a thermally stable in-situ nanoindenter, repeated indentation creep tests were performed on nanocrystalline (nc) nickel (Ni), and the results were systematically compared with corresponding micropillar compression experiments. To explore the influence of tip geometry and material response, two distinct non-self-similar indenter geometries, spherical and cylindrical flat punch indenters, were used. The spherical indenter exhibited a linear decay in stress relaxation with increasing depth, while the flat punch showed minimal stress relaxation (similar to 10 MPa) on nc Ni. This behavior is reflected in the extracted activation parameters: for the spherical indenter, the activation volume increased linearly with representative indentation strain from 4.25 to 13.7 b(3), whereas for the flat punch, it remained stable at 11.8 +/- 1.5 b(3). Due to obtaining consistent activation parameters with the cylindrical flat punch, it was further used to perform repeated indentation creep tests on single-crystal chromium (sx Cr) and single-crystal nickel (sx Ni). These tests demonstrated the reliability of the cylindrical flat punch geometry in capturing activation parameters across different material systems.

Femtosecond laser machining has become a key tool to fabricate micromechanical test samples. However, the potential effect of a heat affected zone (HAZ) remains a concern. In this work, an approach of rapidly processing micromechanical test specimen using a joint fs-laser and focused ion beam approach is shown, drastically reducing time spent on sample preparation. This process is displayed on a heat sensitive material, gallium, to physically show the minimal HAZ and lack of heat accumulation effects in the process and establish a basis for further fs-laser usage in micromechanics.

The increasing demand for highly specialized advanced materials requires a comprehensive understanding of the relationship between processing conditions and the resulting mechanical properties. This study investigates the structure-property relationship of pure tungsten and potassium-doped tungsten fine wires, focusing on material hardness as a function of deformation state and annealing treatment. Hardness was evaluated using nanoindentation and microhardness testing, respectively. The results show a monotonic increase in hardness with increasing amount of deformation, with pure tungsten exhibiting slightly higher hardness than potassium-doped tungsten except at the highest deformation levels. The measured hardness ranged from approximately 13 GPa to 15 GPa depending on the deformation condition. Recovery annealing (400–500°C) led to further increases in hardness, indicating annealing-induced hardening effects. In contrast, high-temperature annealing up to 2400°C resulted in grain growth from approximately 100 nm to 500 nm and a corresponding decrease in hardness for potassium-doped tungsten, from approximately 8.5 to 4.5 GPa. The findings demonstrate the combined influence of deformation and thermal treatment on hardness evolution in tungsten fine wires and provide insight into microstructure-dependent strengthening mechanisms.

Die Erforschung und Entwicklung innovativer Werkstoffe bilden den Schlüssel für zukunftsweisende Technologien und sichern die globale Wettbewerbsfähigkeit des Standorts Österreich. Dies gilt insbesondere in Hinblick auf die Forschungsgebiete der Quantentechnologien, Mikroelektronik, Energieumwandlung und -speicherung, Mobilität, Medizintechnik und Raumfahrt. Neben experimentellen Untersuchungen wird dabei immer stärker auf die begleitende Modellierung und Simulation des Werkstoffverhaltens zurückgegriffen. Die Montanuniversität Leoben bietet mit ihrem breiten Studienangebot, internationalen Forschungskooperationen und engen Industriekontakten die idealen Voraussetzungen, um die technologischen Herausforderungen unserer Zeit zu meistern. Um zum einen die Zusammenarbeit zwischen den Forschenden an der Montanuniversität Leoben zu stärken und zum anderen die Kommunikation nach außen im Bereich Werkstoffe zu forcieren, wurde der Exzellenzcluster Werkstoffe mit Anfang des Jahres 2026 ins Leben gerufen.

Metal hydrides remain an intriguing alternative to conventional gaseous and liquid hydrogen storage methods, offering high volumetric storage density and enhanced hydrogen storage safety at ambient conditions. In this regard, the intermetallic compound FeTi is one of the most promising storage materials. However, its widespread industrial application remains challenging due to the need for activation, slow initial kinetics, large hysteresis, and high material costs. In this study, we aim to overcome these limitations by devising an alternative synthesis pathway to prepare nanoporous and ultra-fine porous FeTi with controlled grain and ligament sizes, allowing us to study the obtained well-defined microstructures in detail. In particular, we observe the confinement of the FeTi phase by surface oxides, which can be correlated with the hydrogen sorption properties of the respective material. These experimental results are further supported by an analytical model allowing the calculation of the absorption pressure as a function of microstructure-dependent elastic stresses. Additionally, we show that such stresses also influence the absorption-desorption hysteresis. This study lays the groundwork for the controlled and systematic study of the processing-structure-properties relations in metal hydrides and FeTi in particular, thereby paving the way to cost-effective and efficient hydrogen storage solutions based on metal hydrides.

Materials engineered to endure extreme environmental conditions face a challenging balance between temperature resistance and vexing strength-toughness trade-offs. Body-centered cubic refractory alloys are attractive for their exceptional strength at elevated temperatures, yet at ambient conditions, they tend to exhibit ceramic-like behavior characterized by low toughness and ductility. In this work, we demonstrate a metastability alloy design approach using oxygen interstitials to generate a hierarchical microstructure in equiatomic TiNb with a strength exceeding 2 GPa in tension while retaining moderate initiation fracture toughness. These exceptional properties, measured site-specifically using nanoindentation and micro-tensile tests, are linked to phase decomposition pathways arising from oxygen-induced immiscibility, including spinodal decomposition with nanoscale compositional undulations and the simultaneous emergence of a dual-phase lamellar structure. These microstructures feature nanoscale domains that can be described via a structural evolution along the Burgers pathway, including intermediate orthorhombic structures, which act in concert to provide obstacles to dislocation glide at multiple length scales. In situ tensile experiments demonstrate that dislocation-mediated plasticity is difficult in the spinodal-like regions, whereas dislocation glide can occur readily within the Nb-rich BCC lamellae, facilitating more uniform plasticity. The interstitial engineering approach shown here integrates nanostructured architectures, strength, and toughness reminiscent of advanced steels with the potential for high-temperature structural applications.

Micro- and nanostructural fabrication is oftentimes limited to planar top-down approaches such as classical lithography, ion- or laser ablation. This makes complex three-dimensional structures akin to macroscopic structures rather challenging to produce. However, recent developments in polymerization techniques enable a true free-from additive manufacturing approach with a resolution of tens of nanometers. Here we provide a short overview of the technique, detail initial experiments that achieved tailorable mechanical and optical properties, and outline future prospects.

The presented study focuses on the analysis of fatigue crack growth rate (FCGR) in focused ion beam-notched microcantilevers prepared from nanocrystalline (NC) Ni as a model material. The results are directly compared to the previously obtained data on NC Ni with mesoscale and macroscale test specimens. The fatigue crack growth threshold Delta K-th range was measured to be in the range of 1.5-2.3 MPa & centerdot;m(-1/2 )in microscale samples. This value compares well with macroscopic samples showing Delta K-th approximate to 2 MPa & centerdot;m(-1/2) measured for R = 0.1 and R = 0.7. Due to the microcantilever width and thickness of similar to 5 & micro;m, such microscale specimens do not exhibit any crack closure effects, and the fatigue crack growth initiation threshold is identical to the effective threshold. However, the effect of previous loading history was shown to have a noticeable effect on the crack growth rate after growth initiation, associated with the change of crack tip geometry and formation of surface extrusions/intrusions at the crack tip. It was also observed that the methodology for the Delta K-driven FCGR testing in cantilevers with microscopic dimension is limited to small Delta K (<2 MPa & centerdot;m1/2), as it does not sufficiently describe the fatigue process at higher Delta K due to considerable sample plasticity.

Understanding and evaluating the fracture behaviour of micro-architected multilayer systems is essential to ensure structural integrity. This work proposes a novel hybrid experimental-computational framework to characterise the fracture toughness of coatings at the micrometre scale. Pre-notched micro-cantilever tests were performed on TiN-coated FeCr specimens fabricated by focused ion beam machining. The tests provided load-displacement curves and direct observations of crack propagation within the TiN layer and subsequent TiN-FeCr interface delamination. Residual stresses resulting from the TiN deposition were quantified experimentally and incorporated into the simulations through an eigenstrain-based approach, enabling the representation of deposition-induced stresses, their redistribution during micro-cantilever fabrication, and their role in crack initiation and growth. A generalised cohesive phase-field model was developed and validated against the experiments to capture the two key fracturing processes involved. The TiN layer was described by an orthotropic phase-field formulation to represent its anisotropic fracture response, while the FeCr substrate was modelled as an elastoplastic material. The proposed methodology successfully reproduces the experimental fracture sequences and allows the intrinsic toughness of the TiN layer to be distinguished from the effects of residual stress. Furthermore, it enables a consistent identification of the TiN-FeCr interfacial decohesion properties, accounting for substrate plasticity. The successful application of the proposed approach opens new avenues for advanced structural assessments of coated microstructures and thin-film systems, widely found in advanced engineering applications, and provides a general pathway to incorporate eigenstrain-based residual stress fields, anisotropic fracture, and elastoplastic substrate effects in phase-field analyses of micro components.

This work uses high-pressure torsion (HPT) to fabricate nanostructured graphite-reinforced Inconel 718 metal matrix composites. The initial powders were pretreated by a colloidal mixing (CM) step to mitigate graphite particle agglomeration and improve the powder blend homogeneity. Scanning electron microscopy investigations show the formation of a nanocrystalline solid solution of the Inconel 718 matrix. Comprehensive statistical image analysis is used to study graphite evolution after deformation in dependency of concentrations and processing routes. It is shown that CM improves composite processability, significantly reducing graphite agglomerate size (80 pct), and improving graphite distribution homogeneity. Raman spectroscopy measurements reveal the structural state of graphite, showing a minimal effect of CM on graphite defect density, while HPT induces a significant increase. Despite the structural degradation, no amorphization is observed, and crystalline domain sizes remain constant in the nanocrystalline range, independent of the applied shear strain. The nanoindentation hardness tested at room temperature is higher for graphite-reinforced composites compared to the Inconel 718 reference alloy. High-temperature in situ nanoindentation tests reveal that the indentation hardness of the CM-processed composite measured at 823 K even surpasses the hardness of the pure reference alloy at room temperature.

The integrity of structural materials is oftentimes defined by their resistance against catastrophic failure through dissipative plastic processes at the crack tip, commonly quantified by the J -integral concept. However, to date the experimental stress and strain fields necessary to quantify the J -integral associated with local crack propagation in its original integral form were inaccessible. Here, we present a multi-method nanoscale strain- and stress-mapping surrounding a growing crack tip in two identical miniaturized fracture specimens made from a nanocrystalline FeCrMnNiCo high-entropy alloy. The respective samples were tested in situ in a scanning electron microscope and a synchrotron X-ray nanodiffraction setup, with detailed analyzes of loading states during elastic loading, crack tip blunting and general yielding, corroborated by a detailed elastic-plastic finite element model. This complementary in situ methodology uniquely enabled a detailed quantification of the J -integral along different integration paths from experimental nanoscale stress and strain fields. We find that conventional linear-elastic and elastic-plastic models, typically used to interpret fracture phenomena, have limited applicability at micron to nanoscale distances from propagating cracks. This for the first time unravels a limit to the path-independence of the J -integral, which has significant implications in the development and assessment of modern damage-tolerant materials and microstructures.

Dislocations of the (c+a) type are widely recognized as the primary defects limiting the ductility of magnesium. While their glide can be activated in small magnesium crystals under high flow stresses, our in-situ transmission electron microscopy compression tests, conducted over a large strain range, reveal that (c+a) dislocation plasticity becomes inactive following initial activation, leading to dislocation avalanches and subsequent deformation twinning. Initially, pyramidal II slip mediated by (c+a) dislocations accommodates plastic deformation in caxis-oriented magnesium pillars under compression. However, as deformation progresses, interactions among dislocations increasingly impede further glide and prevent surface annihilation. Correlative atomistic simulations indicate that this limited dislocation plasticity arises from the formation of basal I1 and I2 stacking faults, generated by interactions between glissile pyramidal II dislocations. The restricted motion of (c+a) dislocations consequently results in stress accumulation, which triggers dislocation avalanches and deformation twinning. This deformation behavior fundamentally differs from the typical dislocation starvation or exhaustion mechanisms observed in small-scale plasticity, offering novel insights into plasticity and work hardening in bulk magnesium.

This study investigates the microstructure evolution and mechanical behavior of bimodal-sized sintered copper (Cu) nanoparticles (NPs) under varying sintering pressures. Micro-pillar compression tests reveal a transition from collapse-dominated to compaction-driven deformation as sintering pressure increases. Transmission electron microscopy (TEM) and transmission Kikuchi diffraction (TKD) analyses identify a two-stage deformation mechanism-initial pore compaction followed by intragranular slip-fundamentally distinct from bulk Cu. Molecular dynamics (MD) simulations further reveal that large particles promote dislocation-mediated plasticity by accommodating intragranular slip, while small particles enhance load transfer through localized shear-compaction, together enabling uniform strain distribution and supporting the experimentally observed strain accommodation. The resulting microstructure achieves a combination of high yield strength (up to 320 MPa) and low elastic modulus (20 GPa), offering a compliant yet robust response. These findings elucidate a unique processing-structure-property relationship and provide a rational basis for designing porous metal interconnects capable of withstanding thermomechanical stresses in advanced electronic packaging.

Hydrogen is key in reducing greenhouse gas emissions in materials production. At the same time, it significantly affects mechanical properties, often causing unwanted embrittlement. However, rather than solely addressing these disadvantages, hydrogens inevitable role in sustainable metallurgy should be leveraged to create new and potentially superior materials. Here, we show that using hydrogen in the form of metal hydrides introduces a barrier to mechanical alloying, stabilizing otherwise unattainable microstructures. Severe plastic deformation of a composite of the high entropy alloy (HEA) TiVZrNbHf and Cu leads to amorphization while substituting the HEA by its hydride preserves the two-phase structure. Monte Carlo simulations confirm that the significantly different hydrogen affinities, together with the restricted dislocation motion in the hydride, create a barrier to mechanical alloying. This hydride route enables new microstructural states, even in well-studied material systems. It opens an additional dimension in designing materials with diverging hydrogen affinities, offering tighter control over mechanical alloying.

Efficient water splitting is a major challenge in green hydrogen production and energy transition. Thus, considerable scientific efforts are devoted to optimize surface geometries for enhancing the performance of water-splitting catalysts. The current study aims to develop a reliable and facile 3-step (re-)production technique for manufacturing structured surfaces by combining multi-photon lithography (MPL) and nanoimprint lithography (NIL). MPL enables structuring of high-definition micrometer-scale surface geometries. A variation of these topologies was used as masks for replication by NIL. Thus, molds were derived to emboss the original nanostructured topologies repeatedly into a UV-curable resin. Subsequently, a Ni thin film metallization was deposited by physical vapor deposition onto the final imprinted polymeric structures, thereby realizing topologically structured conductive electrodes. To demonstrate the applicability of this elaborated technique, the catalytic activities towards the hydrogen evolution reaction were assessed for different surface geometries. An increase in catalytic performance was achieved through surface enlargement by structuring, whereby a direct contribution of the specific structure geometry was not evident. This elegant method is highly versatile and scalable for producing a wide range of structured functional surfaces on a lab scale, as demonstrated for the water splitting reaction, with results transferable to an industrial scale.

By utilizing a novel, green and efficient spark plasma ablation deposition, <10 nm size titanium nitride nanoparticles were obtained. The prepared nanopowder material can be utilized for the deposition of a nanocrystalline thin film. The solid-state synthesis was performed completely at ambient conditions, without the use of solvents and post-processing. Transmission electron microscopy confirmed the size of the nanoparticles within the range of less than 10 nm with primary particles as small as 3 nm, while selective area diffraction confirmed fits cubic titanium nitride (TiN) crystal structure. The geometry (thickness and surface roughness) of the deposited thin films could be varied depending on the sparking current and flow rate. Raman spectroscopy suggested the specific morphology that stems from the plastic deformation of nanoparticles upon collision with the substrate might influence the nanolocal structural environment due to a high surface contribution of tensile stress.

This work investigates the micromechanical deformation behavior of monocrystalline [1 0 0]-oriented silicon micropillars at high temperatures, focusing on the range between 500 degrees C and 900 degrees C. A significant reduction in material strength is observed with increasing temperature. Tests at varying strain rates indicate a change in the deformation mechanism with increasing temperature. Correlative post-deformation TEM characterization was employed to detail the microstructural origins. Indeed, a gradual transition was unveiled. While plasticity is almost exclusively dominated by twinning through the glide of leading Shockley partial dislocations at 500 degrees C, a gradual transition towards full dislocations is observed with increasing temperature. While this transition has been previously observed in macroscopic samples, this study further delves into the strain rate-dependent hightemperature plasticity of silicon at small scales, reporting valuable mechanistic data highly relevant for miniaturized silicon structures in modern information technology.