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In this study, the layered structures of immiscible Fe and Cu metals were employed to investigate the interface evolution through solid-state mixing. The pure Fe and Cu powders were cold-consolidated by high-pressure torsion (HPT) to fabricate a layered Cu-Fe-Cu structure. The microstructural evolutions and flow of immiscible Fe and Cu metals were investigated following different iterations of HPT processing. The results indicate that the HPTprocessed sample following four iterations showed a sharp chemical boundary between the Fe and Cu layers. In addition, the Cu powders exhibited perfect consolidation through HPT processing. However, the Fe layer contained many microcracks. After 20 iterations of HPT, the shear strain generated by HPT produced interface instability, which caused the initial layered structure to disappear.

Scripta materialia 206, 114219 (2022). doi:10.1016/j.matdes.2021.109533, In this work, laser welding of a rolled CoCrFeMnNi high entropy alloy to 316 stainless steel was per- formed. Defect-free joints were obtained. The microstructure evolution across the welded joints was as- sessed and rationalized by coupling electron microscopy, high energy synchrotron X-ray diffraction, me- chanical property evaluation, and thermodynamic calculations. The fusion zone microstructure was com- posed of a single FCC phase, and a hardness increase at this location was observed. Such results can be attributed to the formation of a new solid solution (arising from the mixing of the two base materials). Moreover, the incorporation of carbon in the fusion zone upon melting of the stainless steel also aids in the strengthening effect observed. The welded joints presented good mechanical properties, with fracture occurring at the fusion zone. This can be ascribed to the non-favourable, i.e., large grain size, microstruc- ture that developed at this location., Published by Elsevier Science, Amsterdam [u.a.]

A strategy to improve the tensile properties of Co17.5Cr12.5Fe55Ni10Mo5 (at%) medium-entropy alloy through high-pressure torsion and subsequent annealing is presented in this work. Microstructural study revealed that the high-pressure torsion process led to the formation of fine grains (≤~1 μm) and profuse nano-scale Mo-rich μ-phase precipitates. And resultantly, the yield strength of the alloy was tuned from ~400 MPa to ~1 GPa, while preserving reasonable uniform elongation over 15%. The combination of strengthening from grain refinement and precipitation contributed to the excellent strength, while the post-HPT annealing provided substantial ductility.

We investigated the stretch-flangeability of CoCrFeMnNi high-entropy alloy (HEA) in comparison with other face-centered cubic alloys (304 stainless steel and twinning-induced plasticity steel). The hole expansion ratio of the HEA was superior to those of the other alloys, attributed to fewer vulnerable sites for crack-initiation and the resulting high crack-resistance.