At the interface of thin film development and powder metallurgy technologies, this study aims to characterise the mechanical properties, lattice constants and phase formation of Ti-Nb alloys (8–30 at.%) produced by different manufacturing methods, including conventional powder metallurgy (PM), mechanical alloying (MA) and high power impulse magnetron sputtering (HiPIMS). A central aspect of this research was to investigate the different energy states achievable by each synthesis method. The findings revealed that as the Nb content increased, both the hardness and Young’s modulus of the PM samples decreased (from 4 to 1.5 and 125 to 85 GPa, respectively). For the MA alloys, the hardness and Young’s modulus varied between 3.2 and 3.9 and 100 to 116 GPa, respectively, with the lowest values recorded for 20% Nb (3.2 and 96 GPa). The Young’s modulus of the HiPIMS thin film samples did not follow a specific trend and varied between 110 and 138 GPa. However, an increase in hardness (from 3.6 to 4.8 GPa) coincided with an increase in the β₂ phase contribution for films with the same chemical composition (23 at.% of Nb). This study highlights the potential of using HiPIMS gradient films for high throughput analysis for PM and MA techniques. This discovery is important as it provides a way to reduce the development time for complex alloy systems in biomaterials as well as other areas of materials engineering. Graphical abstract

This study systematically compares the surface polishing performance and finishing results of the following two different electrolytic plasma polishing technologies on stainless steel AISI 316L: (i) plasma electrolytic polishing (PEP) and (ii) plasma electrolytic polishing jet (PEP-Jet). The two techniques are compared against an industrial standard polishing method, electropolishing (EP). For comparable energy density consumption, the samples treated with the PEP-Jet technique showed the highest removal rate, up to three times less than the initial roughness, resulting in the highest surface roughness reduction from Sa = 249 nm to Sa = 81 nm. Microstructure characterization of samples treated using PEP-Jet also showed well-defined crystalline grain boundaries with a distinct appearance of predominantly inter-crystalline structures within individual grains, which is uncommon with EP techniques. The surfaces treated using PEP-Jet exhibited the lowest corrosion rate of $6.79\times {10}^{-5}$ mm/year, and no signs of areal corrosion were detected in the performed corrosion tests in contrast with the other samples and their respective treatments. The comparative analysis revealed that the high ionic current delivered by the electrolyte jet flow in the PEP-Jet process effectively stabilizes the plasma at the contact zone, thereby enhancing the plasma polishing of austenitic stainless steel samples. The efficacy of this method has been demonstrated in terms of reducing energy consumption and enhancing corrosion resistance in comparison with (PEP) and (EP) as state-of-the-art processes in corrosive environments of high-alloyed steel.

A combinatorial material adhesion study was used to optimize the composition of an adhesion promoting layer for a nanocrystalline diamond (NCD) coating on silicon. Three different adhesion promoting metals, namely W, Cr, and Ta, were selected to fabricate arrays of co-sputtered binary alloy films, with patches of seven different, distinct alloy compositions for each combination, and single element reference films on a single Si wafer (three wafers in total; W–Cr, Cr–Ta, Ta–W). Scratch testing was used to determine the critical failure load and practical work of adhesion for the NCD coatings as a function of adhesion layer chemistry. All tested samples eventually exhibit delamination of the NCD coating, with buckles radiating perpendicularly away from the scratch track. Application of any of the presented adhesion layers yields an increase of the critical failure load for delamination as compared to NCD on Si. While the influence of adhesion layers on the maximum buckle length is less pronounced, shorter buckles are obtained with pure W and Cr–Ta alloy layers. As a general rule, the addition of an adhesion layer showed a 75% improvement in the measured adhesion energies of the NCD films compared to the NCD coating without an adhesion layer, with specific alloys and compositions showing up to 125% increase in calculated practical work of adhesion.