Hot stamping also known as press hardening is one of the most important processes for manufacturing components with strengths exceeding 1500 MPa. The process combines heat treatment and forming in a single operation. Heating is typically carried out in gas-fired roller hearth furnaces and, due to the AlSi coating, requires slow heating times of 6-10 min. For alternative heating methods such as resistance heating, only uncoated sheet material can be used. However, during rapid heating rates of more than 100 K/s, the sheets suffer from scaling, which makes costly postprocessing necessary. This study demonstrates that by using a protective atmosphere of nitrogen and monosilane, a process environment can be created that corresponds to the oxygen concentration of an extreme high vacuum. At the same time, this process atmosphere enables the in-situ coating of uncoated sheets with the process heat required for hot stamping. Furthermore, it is shown that coating materials can be applied which form intermetallic phases.

Niobium-zirconium alloys like Nb-1Zr offer high biocompatibility and osteoconductivity, with a lower Young's modulus than Ti-6Al-4V, but their strength is limited due to a coarse grain structure. In this study, alloy strength is enhanced through controlled internal oxidation. Pre-oxidizing Nb-1Zr powder at 620 degrees C for 0, 60, and 120 min prior to co-extrusion increased 0.2% offset compression yield stress from 829 to 937 MPa. The improved strength is due to a fine-grained structure and high dislocation density. Longer oxidation times increased brittle niobium oxides. Future work will refine oxidation to tailor the properties of these alloys for load-bearing implants. (c) 2026 The Author(s). Published by Elsevier Ltd on behalf of Society of Manufacturing Engineers (SME). This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

High entropy shape memory alloys (HE-SMAs) combine unique high entropy-based properties with the functional advantages of shape memory alloys. Specifically, they feature enhanced strength, adjustable transition temperatures, high recoverable stresses and thermal stability. However, common challenges in multicomponent alloy design such as segregation and secondary phases hinder their functionality. The effectiveness of conventional heat treatments in overcoming these challenges is often limited, resulting in sub-optimal performance of promising alloy systems. This study investigates the benefits of thermo-mechanical processing (TMP) as a strategy to control the homogeneity and microstructure of HE-SMAs and thereby increasing their functionality. It focusses on the NiTi-related alloy Ti16.6Zr16.6Hf16.6Co10Ni20Cu20, evaluating the effects of TMP on its microstructural evolution and mechanical performance with the goal to establish reliable functionality. By employing TMP via hot-extrusion, significant improvements in microstructural homogeneity and both mechanical and functional properties were achieved. The effects of TMP included enhanced structural integrity after forming, a 25

The high oxygen affinity and tendency to nitride formation in the presence of nitrogen represent a major challenge for the application of thermally sprayed titanium coatings. Thus, there are only two established thermal spraying processes to produce titanium coatings, i.e., cold gas spraying and vacuum spraying. The present study was designed to overcome previous limitations by transferring the coating process to a silane-doped argon gas environment to obtain extremely low oxygen partial pressure (p(02) < 10(-23) Pa). With this approach, oxide-free titanium coatings could be realized with a wire arc spraying system, which is a process that is otherwise unsuitable for the application of materials with high oxygen affinity. The coatings created are oxide- and nitride-free and feature low porosity. Moreover by transferring the corundum blasting process to this environment, the native oxide film on the substrate surface is removed and its reformation suppressed. Thus, full material bonding conditions are created, resulting in extremely high adhesive tensile strengths.

Solid-state diffusion and intermetallic phase formation were examined in roll-bonded magnesium alloy-zinc (Mg-Zn) composites that contain a kirigami-patterned magnesium alloy (ZX10) inlay. The kirigami-patterned inlay was embedded between two zinc sheets and roll-bonded at 310 degrees C. Subsequent heat treatments at 318 degrees C and 328 degrees C promoted interfacial diffusion as well as the formation of intermetallic phases. The kirigami geometry of the inlay was employed as a process-level tool to impose spatially inhomogeneous deformation during roll bonding. This caused localized stress concentrations, driving the controlled transformation of the initial pattern within the deformation zone. It also prevented the thin inlay from failing prematurely and ensured its controlled distribution along the sample. Inhomogeneous strain distribution introduced three-dimensional diffusion pathways that activated bonding and initiated phase transformation. Flexural testing revealed a significant increase in mechanical strength compared to values calculated using the rule of mixtures. The maximum strength observed was 100 MPa for samples heat-treated at 318 degrees C. Microstructural analyses showed a progression from adhesive bonding (group A) to uniform intermetallic layers (group B) and complex, multiphase regions containing eutectic, dendritic, and porous fractions (group C). Energy-dispersive X-ray spectroscopy confirmed zinc diffusion into the magnesium solid solution, indicating the onset of solid-state alloying. The combined effects of plastic deformation, thermal activation, and the kirigami-patterned Zn inlay resulted in Mg-Zn composites with enhanced interfacial integrity and a tailored phase composition. These composites offer a promising pathway for advanced material compounds to be used in biomedical and mechanical applications.

The effect of minor compositional variations on the martensitic transformation and the magnetic properties of CoNiAlFe alloys was investigated using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, magnetic measurements, and in situ SEM observations. Samples taken from the same bulk material with the nominal composition Co35Ni35Al28Fe2 (at. −

This work addresses a central challenge in Al-Cu compound casting: native copper oxides, which inhibit wetting and metallurgical bonding. A laser-based deoxidation strategy (ns-pulsed, 1064 nm) performed under oxygen-free, XHV-equivalent glovebox conditions, and quantifying subsequent oxide regrowth during realistic short-term handling, is demonstrated. Surface roughness was tuned via pulse/line overlap (0% vs. 70%) and characterized using confocal microscopy and power spectral density analysis. X-ray photoelectron spectroscopy reveals that laser processing under XHV-equivalent conditions produces copper surfaces that are more than 98% oxide-free and remain predominantly metallic for at least 720 h, whereas exposure to ambient air rapidly leads to the formation of a Cu2O/Cu(OH)2 surface layer within 24 h. Subsequent post-treatment heating promotes the transformation CuO CuO, in accordance with established low-temperature oxidation pathways. Casting under XHV-equivalent conditions yields fully bonded Al-Cu interfaces with the expected Al2Cu, AlCu, and Al4Cu9 intermetallic layers. Intermetallic compound (IMC) morphology is more strongly governed by processing parameters (temperature, expected melt-to-solid ratio, and thermal history) than by minor short-term oxide regrowth. Overall, laser deoxidation under XHV-equivalent conditions emerges as a pretreatment that improves wetting, enables controllable IMC formation, and preserves high interfacial thermal conductivity in Al-Cu composite castings.

Titanium nitride (TiN) coatings are widely used as wear-protection layers on cutting and forming tools due to their high hardness and chemical stability. However, the adhesion of TiN on substrates, such as silicon and steel (1.4301), can be insufficient for a given application. This study investigates the effect of atmospheric pressure plasma pretreatment on the adhesion behavior of TiN coatings. The surface modification is analyzed using confocal laser scanning microscopy after plasma treatment with argon (Ar) and argon/hydrogen (Ar/H2) gas mixtures. Subsequently, the samples are coated by reactive magnetron sputtering. Adhesion performance is evaluated by cross-cut test, while X-ray diffraction is employed to detect possible changes in the crystalline structure of the coatings. Plasma treatment deoxidizes and activates the surface, which enhances adhesion between coating and substrate. Ar/H2 plasma, in particular, significantly improves coating adhesion compared to untreated samples. These findings demonstrate that plasma-surface pretreatment improves coating durability and has the potential to extend tool lifetime in industrial applications.

Microstructure, hardness, physical properties, and corrosion response of Al‐Cu intermetallic compounds (IMCs) are investigated with the aim of establishing optimization guidelines for the Al‐Cu bimetallic compound casting process. Five Al‐Cu samples with chemical compositions promoting stable single phases ( and at ambient temperature are produced via induction casting. The microstructural and compositional analysis, however, evidenced the precipitation of secondary phases in the and θ samples. It is also observed that θ can directly transform into , due to a kinetically enabled process. Physical properties, including electrical conductivity, thermal diffusivity, and specific heat, are measured, and the thermal conductivity is calculated accordingly. It is observed that the copper‐rich IMCs have lower thermal conductivity compared to other Al‐Cu IMCs. The nonmonotonous relationship between physical properties and chemical composition is correlated to the crystallography of the phases and the precipitation of secondary phases. Experimental validation demonstrated a significant impact of casting defects (over 30%) on the thermal conductivity of the interfaces. Moreover, the overall hardness of cast samples showed significant deviation from previous studies, emphasizing the impact of the sample production method. Finally, corrosion assessment using a 0.5% NaCl solution suggested galvanic corrosion as the primary corrosion mechanism.

Laser surface texturing enables precise control of micro-and nano-scale topographies that govern wettability, adhesion, friction, and interfacial bonding. In this study, nanosecond-pulsed laser ablation under oxygen-free processing conditions is established as a scalable and automation-ready approach for the simultaneous removal of native oxides and the functional texturing of aluminum and copper surfaces for advanced manufacturing applications. By systematically varying pulse overlap, surface morphologies are tuned from isolated ablation craters to homogeneous textures and, at high overlap, to a melt-dominated regime with increased roughness and effective surface area, enabling application-specific tailoring of interfacial properties. Material-dependent near-surface modifications are observed: aluminum exhibits increased hardness and stiffness, while copper shows localized softening, highlighting fundamentally different laser-matter interaction mechanisms relevant for surface engineering. Microstructural evolution and residual stress development depend on overlap and accumulated fluence, with high overlap promoting texture reduction and stress relaxation. X-ray photoelectron spectroscopy confirms effective oxide removal and exposure of metallic copper under oxygen-free conditions, while identical processing in air leads to pronounced reoxidation; aluminum shows the same qualitative trend. The functional relevance of laser-textured, oxide-free surfaces is demonstrated for adhesive bonding, cold roll bonding, compound casting, and laser beam brazing, enabling improved wetting, enhanced interfacial adhesion, reduced critical deformation for solid-state bonding, and flux-free aluminum-copper joining. The results establish oxygen-free ns-pulsed laser ablation as a versatile surface engineering route that integrates cleaning, oxide-removal and functional structuring in a single step, offering broad potential for advanced and automated manufacturing in joining processes.

Cold roll bonding (CRB), a process that conventionally requires high degrees of deformation, is employed under extreme high vacuum (XHV)-adequate conditions to promote bond formation. Specifically, surface pretreatments via laser ablation and mechanical brushing are compared for Cu-Al bonding in oxygen-free environments with a focus on bond strength evolution, interface morphology, residual stress states and crystallographic texture development. Laser ablation treatment led to superior bond strengths at all tested reduction levels, while both methods converged to similar strength values at high deformation levels. Laser ablation creates interfaces with increased true contact area through enhanced microscopic irregularities. Residual stress measurements show that laser ablation induces beneficial residual tensile stresses, whereas brushing generates residual compressive stresses. In addition, laser-treated specimens retain preferred cube textures at the surfaces for both bonding partners, reducing crystallographic mismatch. The enhanced performance of laser ablation arises from synergistic mechanisms, as detailed in a multimechanistic framework to foster understanding of CRB under oxygen-free conditions.

Retained austenite is an essential structural component of rolling bearing steels, which significantly influences their mechanical and tribological properties. Although conventional quantification of the retained austenite content using X-ray diffraction provides high accuracy, it is time-consuming and unsuitable for process-integrated applications. Therefore, this study investigates the suitability of a multi-frequency electromagnetic testing method for the non-destructive determination of the retained austenite content in 100Cr6 and 100CrMn-Si6-4. A wide range of retained austenite contents was generated by systematically varying the austenitising and tempering temperatures. Strong correlations (r values of up to 0.97) were obtained between signal components and retained austenite content. Regression models based on these correlations enable reliable prediction of the retained austenite content. The results demonstrate the potential of harmonic analysis of eddy current signals for fast and process-oriented quality control of heat-treated components. However, additional microstructural changes may also influence the electromagnetic response and must be considered in robust quantitative evaluation. Restaustenit ist ein wesentlicher Gef & uuml;gebestandteil von W & auml;lzlagerst & auml;hlen, der deren mechanische und tribologische Eigenschaften ma ss gebend beeinflusst. Die konventionelle Quantifizierung des Restaustenitanteils mittels R & ouml;ntgendiffraktometrie liefert zwar hohe Genauigkeit, ist jedoch zeitaufwendig und f & uuml;r prozessintegrierte Anwendungen ungeeignet. In dieser Arbeit wurde daher die Eignung eines mehrfrequenten elektromagnetischen Pr & uuml;fverfahrens mit Oberwellenanalyse zur zerst & ouml;rungsfreien Bestimmung des Restaustenitgehalts in den Werkstoffen 100Cr6 und 100CrMnSi6-4 untersucht. Durch systematische Variation der Austenitisierungs- und Anlasstemperaturen wurde ein breites Spektrum an Restaustenitgehalten erzeugt. Es konnte gezeigt werden, dass eine starke Korrelation zwischen den harmonischen Signalanteilen und dem Restaustenitgehalt besteht. Die entwickelten Regressionsmodelle erlauben eine zuverl & auml;ssige Vorhersage des Restaustenitgehalts. Die Ergebnisse zeigen das Potenzial der Harmonischen Analyse von Wirbelstromsignalen f & uuml;r eine schnelle und prozessnahe Qualit & auml;tskontrolle w & auml;rmebehandelter Bauteile. Zus & auml;tzliche mikrostrukturelle Ver & auml;nderungen k & ouml;nnen das Messsignal jedoch beeinflussen und sind bei einer robusten quantitativen Auswertung zu ber & uuml;cksichtigen.

Cutting inserts experience substantial mechanical and thermal loads during machining. Hard thin-film coatings are widely applied to enhance performance and durability, but their residual stresses critically affect adhesion, stability, and tool life. Common stress determination methods include X-ray diffraction (sin²ψ; Vm; XRD = 1.3–2.6 mm×3.7 μm), focused ion beam-digital image correlation (FIB-DIC) ring core method (Vm; FIB/DIC = 10 μm×3.7 μm), and Raman spectroscopy (Vm; Raman = 1 μm×40 nm), each deviating in measured volume (Vm = spot size × depth). Our comparative study examines different instrumentation, analysis tools, and applied methods for evaluating residual stresses in physical vapor deposition (PVD)-coated carbide inserts. Results disclose varying susceptibilities depending on thin film characteristics such as thickness, film-substrate interface, texture, chemical and residual stress gradients, highlighting differences in information depth and sensitivity. The study provides a good overview of laboratory methods for determining residual stresses in PVD coating. The sin²ψ-method provides reproducible residual stress states that are independent of varying instruments or analytical methods, including calibrants, radiation, different optics, detectors and even evaluated reflections and are more strongly affected by texture and residual stress gradient. FIB-DIC and sin²ψ method consider the entire cross-section and agree well. FIB-DIC offers higher spatial resolution and is more sensitive to nonuniform chemical influences. In Raman spectroscopy, the bond strength is affected by chemical gradients, among other factors, necessitating an elaborate calibration. Its low penetration depth of a few nanometers and the small spot size cause deviations in the studied heterogeneous thin films.

A numerical model is introduced in which the thermodynamic diffusion approach resulting from irreversible thermodynamics is consistently applied. Unlike Fick's approach that relies on concentration gradients, the thermodynamic approach employs the actual driving force for diffusion, which is the gradient of a component's thermodynamic activity. Utilizing CalPhaD programs to extract component activities from thermodynamic databases, a numerical calculation method was developed and implemented using CUDA C++, in order to apply the thermodynamic model. The model's effectiveness was evaluated using the binary aluminum-iron system, starting from pure metal diffusion couples and simulating interdiffusion until complete mixing under varying conditions. It is shown that the thermodynamic model accurately predicts phase changes and the formation of intermetallic phases using only a singular global diffusion coefficient valid for both components and all phases. The model's application to complex geometries is demonstrated on the alloying of an interpenetrating composite.

Characterizing porous metals requires reliable 3D reconstruction. We compare X-ray computed tomography (XCT) and serial sectioning using a virtual ground truth from segmented XCT data. A GPU-based virtual XCT pipeline simulates imaging artifacts, serial sectioning is modeled via extracted topographies and simulated annealing reconstruction. XCT achieves over 98% accuracy but remains sensitive to segmentation thresholding. Serial sectioning captures visible surfaces precisely but cannot measure occluded regions, yielding lower reconstruction accuracy of 91%. Given these complementary strengths, we propose a hybrid approach where CLSM-derived porosity measurements inform XCT threshold selection, grounding this critical parameter in measured sample properties rather than image statistics alone.

This study showcases machine learning (ML) as a promising tool for developing new biomedical alloys with enhanced corrosion resistance. Specifically, two novel high entropy alloy (HEA) compositions, namely Ti34.8Ta17Nb21.4Zr14.2Mo12.6 and Ti35Ta23Nb20.8Zr14.2Mo7, were predicted as the optimum HEA compositions with enhanced corrosion resistance for orthopedic applications. For validation purposes, potentiodynamic polarization experiments were conducted on the predicted compositions in phosphate buffered saline (PBS) solution at human body temperature, demonstrating the new alloys' superior corrosion properties with the corrosion potential (Ecorr) of-0.40 V +/- 0.05 and-0.46 +/- 0.02 V, respectively. The samples were then subjected to static immersion experiments in PBS for 28 days to gather insight into ion release and for the sake of an initial assessment of the biocompatibility of the new HEAs. The results of this study demonstrate that by employing an optimal combination of feature selection and machine learning models, ML proves to be a powerful tool for predicting HEA compositions with superior corrosion resistance, as evidenced by the close correlation between experimental findings and predicted values reported herein.

This collection provides an overview of current developments in the field of metallic hybrid and porous materials and components made of such materials. Hybrid materials have a locally defined varied material composition while porous materials feature an intentionally cellular material structure. Hybrid porous materials combine both a locally varying material composition and a porous structure. This collection was initiated by the DFG Collaborative Research Centre TRR 375 “Multifunctional High-Performance Components made of hybrid porous materials", which researches the design, manufacture, and characterization of these materials and components. In this collection, the additive manufacturing of hybrid and porous materials is highlighted and methods for the monitoring and control of the manufacturing processes and thus the control of the component properties are pointed out. In addition, approaches to determine the properties of hybrid and porous materials and the application characteristics of hybrid and porous components are outlined. The collection offers insights for those interested in manufacture, characterization, and applications of hybrid porous materials.

Contact Arc Metal Grinding (CAMG) is a fast, robust underwater cutting process. This makes it a potentially valuable solution for nuclear decommissioning. Until now, the measurement of tool wear has been based on parameters such as diameter, volume, or weight of the electrode. All of these variables require direct manipulation and contact with the electrode in order to be determined. In contaminated environments, contactless condition monitoring is crucial. The study proposes and evaluates a signal-based, contactless indicator for tool electrode wear, derived from electrical process data. Transient current signals were transformed into histograms, and the integral over the high-current region was used as a wear descriptor. CAMG trials with various additively manufactured tool electrodes with functional areas (different monolithic metallic alloys and CuSi3Mn1-based composites with fused WC) were conducted under water to evaluate this feature. A dedicated model test setup with different electrodes and high-speed imaging for the isolated observation of individual arc events was designed to facilitate the interpretation of process signals. For monolithic metallic functional areas and a reference steel electrode, the high-current integral decreased monotonically with wear and showed strong, statistically significant negative linear correlations. Despite initial disparities in levels, most notably for the thinner reference disc, all electrodes converged to similar values at the end of service life, once the functional area had been consumed. In contrast, CuSi3Mn1-based composites with fused WC particles exhibited weak or non-significant correlations, consistent with wear-driven changes in surface composition that alter local contact and arc attachment conditions. High-speed imaging was employed to confirm the occurrence of discrete arc events and to demonstrate that discontinuous voltage transients are consistent with rapid current interruptions and inductive voltage spikes. This enabled a correlation previously assumed in the literature to be confirmed experimentally for the first time.

Ein zerstörungsfreies Prüfsystem, das die erfassten Daten drahtlos überträgt und mittels sog. Energy Harvesting oder Batterie betrieben werden kann, ist an Orten einsetzbar, die für eine Inspektion nicht permanent oder nur schwer zugänglich sind. Darüber hinaus kann das Prüfsystem eine kontinuierliche Überwachung gewährleisten, was die Betriebssicherheit verschiedener Bauteile und Strukturen verbessern kann. Im Rahmen des Beitrags wird die Entwicklung eines Prototyp-Prüfsystems vorgestellt. Dieses System besteht aus einem günstigen Wirbelstromsensor, einer energieeffizienten Auswerteeinheit mit einer Ultra-Low-Power-Mikrocontrollereinheit und einer Long-Range Wide Area Network (LoRaWAN) Datenübertragungseinheit. Die drahtlose und energieeffiziente Datenübertragung über LoRaWAN ermöglicht den Zugang zum industriellen Internet of Things und damit die Zusammenführung von Daten mehrerer Sensorsysteme in einer Cloud sowie die Verarbeitung dieser Daten, um den jeweiligen Zustand ortsunabhängig zu beurteilen. Das intelligente Prüfsystem kann hinsichtlich der Funktionalität modular erweitert werden. Mittels Multiplexing können weitere Wirbelstromsensoren verwendet werden. Zudem können weitere Sensoren wie z. B. Temperatur-, Bewegungs- oder Beschleunigungssensoren ergänzt werden. Die Fähigkeit zur drahtlosen Aktualisierung erlaubt zudem eine Anpassung des Auswertealgorithmus, um z. B. zwischen konventioneller Wirbelstromprüfung und Oberwellenanalyse wechseln zu können, oder auch die Anpassung von Alarmschwellen. Primär ermöglicht das System eine Materialcharakterisierung, Fehlerprüfung und Abstandskontrolle. Anwendungsbeispiele können ein Strukturmonitoring von kritischen Stellen an Brücken oder die Überwachung von bereits vorhandenen Rissen an Schweißnähten von Windenergieanlagen sein.