Effects of Thermo-mechanical Treatment on the Microstructures and Mechanical Properties of a Medium-Entropy Alloy

The effects of hot-rolling (HR), cold-rolling (CR), and HR + CR followed by aging on the microstructure mechanical properties medium-entropy alloy (MEA) Ni43.4Co25.3Cr25.3Al3Ti3 were investigated. geometrically-necessary dislocation (GND) density increased with increasing cold rolling reduction to 1.8–2.4 × 1014 m−2, which is eight times 2.9 1013 m−2 found in as-hot-rolled MEA. Higher before led a finer, higher volume fraction L12 nanoparticles as well finer grains, resulted from both accelerated nucleation dislocations and, possibly, pipe diffusion via dislocations. aged MEA exhibited an excellent strength-ductility combination (yield strength ~ 1414 MPa, ultimate tensile 1605 elongation 15%) precipitate strengthening accounting for 26% yield strength, was better than 897 1217 32.3%). A also leads good 1501 1651 20.8%), grain boundary 62% 25% respectively. Substantial partitioning fluctuations principle atoms observed as-CR sample due interacting alloying atoms, i.e. several nano-scaled regions enriched Ni, Al, Ti, depleted Cr Co. In addition, Al Ti have more substantial local composition Co,