Wolfgang Tillmann

Titanium alloys are widely employed for biomedical implants due to their high strength, biocompatibility, and corrosion resistance, yet their lack of intrinsic antibacterial activity remains a major limitation. Incorporating copper, an antibacterial and β-stabilising element, offers a promising strategy to enhance implant performance. This study investigates Ti-6Al-7Nb modified with 1–9 wt.% Cu via in situ alloying during metal-based laser powder bed fusion (PBF-LB/M), with the aim of assessing processability, microstructural evolution, and mechanical properties. Highly dense samples (>99.9%) were produced across all Cu levels, though chemical homogeneity strongly depended on processing parameters. Increasing Cu content promoted β-phase stabilisation, Ti₂Cu precipitation, and pronounced grain refinement. Hardness and yield strength increased nearly linearly with Cu addition, while ductility decreased sharply at ≥5 wt.% Cu due to intermetallic formation, hot cracking, and brittle fracture. These results illustrate both the opportunities and constraints of rapid alloy screening via PBF-LB/M. Overall, moderate Cu additions of 1–3 wt.% provide the most favourable balance between mechanical performance, manufacturability, and potential antibacterial functionality. These findings provide a clear guideline for the design of Cu-functionalised titanium implants and demonstrate the efficiency of in situ alloy screening for accelerated materials development.

Titanium alloys are widely employed for biomedical implants due to their favourable combination of strength, corrosion resistance, and biocompatibility. A drawback, however, is the lack of intrinsic antibacterial functionality. In this study, Ti 6Al 7Nb was modified with varying copper (Cu) contents (1 wt.% – 9 wt.%) via in situ alloying during metal based laser powder bed fusion (PBF-LB/M) to investigate the processing behaviour, microstructural evolution, and mechanical properties. Powder mixtures were processed under systematically varied laser parameters, with densification, surface quality, and microstructure assessed by microscopy and X-ray diffraction, while hardness and tensile properties were characterised through mechanical testing. The results demonstrate that dense samples (> 99.9 %) can be achieved for all investigated copper amounts, although the homogeneity is strongly dependent on the process parameters. An increasing copper content promotes β-phase stabilisation, Ti₂Cu precipitation, and significant grain refinement with a transition from columnar to equiaxed structures. Hardness and yield strength increase nearly linearly with increasing copper content, while the ductility decreases sharply at ≥ 5 wt.% Cu due to intermetallic formation, hot cracking, and brittle fracture mechanisms. These findings highlight both the potential and the limitations of copper additions in Ti 6Al 7Nb processed by PBF LB/M. Overall, moderate additions of 1 wt.% – 3 wt.% Cu appear most promising, offering improved mechanical performance while preserving sufficient ductility and manufacturability for biomedical applications.

Friction-spinning is an incremental thermomechanical forming process that has huge potential due to its simple yet effective mechanism of utilising friction between a rotating workpiece and a forming tool to increase the workpiece’s temperature, which reduces the required forces and increases formability during the forming process. Despite the simplicity of the process’s setup, the thermomechanical loads and high relative velocities involved, especially in the contact zone, make the application of classical methods for characterising friction inaccurate. It is therefore essential to find a way to describe the frictional behaviour under real process conditions to be able to gain a holistic understanding of the process and the effect of the adjustable parameters on the outcome, especially the temperature. To achieve this goal, an experimental setup that considers the actual process boundary conditions in forming tubes made of EN AW-6060 was used to measure in situ normal and frictional forces, in addition to process temperatures, under varying rotational speed and feed rate values.

The continuous improvement of high potential repair technologies is an essential driver for cost-effective and sustainable aviation. To withstand extreme forces and temperatures, the turbine section of aircraft engines is made from Nickel-based superalloys. This class of materials routinely develops cracks and geometrical deviations in service, which require a brazing repair, thus making brazing an indispensable key technology. This study seeks to improve brazing properties on Nickel-based superalloys for aircraft applications. Facilitated by materials simulation, a novel alloying strategy is outlined to design the braze alloy chemistry. The design criteria are established on the optimization of major microstructural properties influencing the mechanical properties known for repair brazed joints. The proposed design criteria were applied to the development of two new braze alloys. The new alloy design approach is validated experimentally by using the developed alloys. Mechanical properties of brazed samples made from Nickel-based superalloys were investigated at a service equivalent temperature of 871 °C. Results indicate that the ultimate tensile strength at 871 °C is 20.5% higher than that published for legacy braze alloys. This study provides a basis for the development of repair technologies applicable to further superalloys.

Great efforts are being made to optimize tool coatings for use at elevated process temperatures. The reason for this is to enable machining with minimized lubrication quantities. During operation, temperatures between 300 and 1000 °C can occur depending on the material and tool design. Thus to enable the machining of high‐strength materials, the tool coatings must be optimized with regard to their temperature resistance, which is also significantly affected by their oxidation properties. AlCrVY(O)N thin films are potential candidates for such coating applications as the addition of V to AlCrN favors the formation of so‐called Magnéli phases at high temperatures, that is, V oxides with varying stoichiometry, to reduce friction. X‐ray absorption spectroscopy is applied to characterize the oxidation behavior of V in the thin films prepared in a combined dcMS/HiPIMS process for as‐deposited AlCrVY(O)N thin films and after thermal treatment in the ambient atmosphere. The V average oxidation state is determined by analyzing the pre‐edge feature at the V K‐edge. Systematic changes in preoxidation, a high oxidation resistance below 800 °C, and promoted V oxidation for higher preoxidized coatings above 800 °C are found.

A Ti‐Si‐C‐N coating is deposited on AISI H11 hot working steel by plasma‐enhanced chemical vapor deposition (PECVD) to investigate its micro‐ and nanostructure as well as its mechanical and thermal properties. Instead of a nanocomposite structure consisting of randomly oriented nanocrystalline (nc‐) grains < 10 nm surround by an amorphous (a‐) matrix, as usually found for these systems, this Ti‐Si‐C‐N coating shows much larger Ti(C,N)‐grains with a preferred (200) orientation identify by X‐ray diffraction analysis. The strong texturing and grain sizes > 10 nm of the coating are confirmed by high‐resolution transmission electron microscopy images. The coating's hardness is 46.3 GPa, making it equally hard to, e.g., nanocomposite Ti‐Si‐N coatings. These hardness values can only be achieved by a strong interface between a‐matrix and nc‐grains and small grain size. Despite 41.1 at.% carbon content, no significant quantity of a‐C is found, as evidenced by Raman spectroscopy analysis. In order to investigate the oxidation behavior of the coatings, X‐ray diffraction experiments are carried out at room temperature and in‐situ in ambient atmosphere at elevated temperatures. The room temperature measurement shows a strong texturing of the Ti(C,N) lattice and yielded additional information on an anisotropic grain size.

The most important cutting materials for machining are carbides. Their production requires both tungsten and cobalt; however, these materials are becoming increasingly difficult to obtain and are sometimes mined under ethically questionable conditions. As a result, increasing efforts are being made to expand the range of cutting materials. The basic suitability of natural rocks for cutting tools in less demanding processes has already been demonstrated. PVD coating of the natural rocks could improve their performance. The adhesion mechanisms in TiN-coated natural rock samples are discussed below. The TiN thin film is characterized in depth.

Ensuring consistent quality in metallurgic Additive Manufacturing (AM) processes, such as Cold Gas Spraying (CGS), is a significant challenge due to the inherent process variability in part quality. This study explores the integration of trustworthy Artificial Intelligence (AI) and the Industrial Internet of Things (IIoT) to multimodal quality control, with the goal of increasing in-situ test coverage of manufactured parts and process stability. An open-source software solution for data engineering and analysis was developed using the Design Science Research methodology. Experiments were conducted on a CGS system utilizing CuZn30, a copper-zinc alloy material, as a representative case study. The developed AI models demonstrated high efficiency in identifying quality deviations across multiple quality characteristics, including oxidation, geometric inaccuracies and porosity (F1-Score=0.998). The results suggest that the combination of IIoT-measurement components and AI is a cost-effective way to significantly improve test coverage, enabling the control of multiple quality attributes and process reliability in metallurgical AM using low-cost sensors and open-source software. This research contributes to the advancement of cost-effective quality control systems and provides a case study of how AI can be used to improve the reliability and stability of advanced industrial manufacturing processes with respect to multiple quality characteristics and data modalities, paving the way for mass customization as proposed in the Industry 4.0 vision.