Influence of Annealing on Microstructure and Mechanical Properties of a Nanocrystalline CrCoNi Medium-Entropy Alloy

摘要: An equiatomic CrCoNi medium-entropy alloy was subjected to high-pressure torsion. This process led a refinement of the microstructure grain size about 50 nm, combined with strong increase in materials hardness. Subsequently, thermodynamic stability medium entropy evaluated by isothermal and isochronal heat treatments. Annealed samples were investigated scanning transmission electron microscopy as well X-ray diffraction, tensile tests establish microstructure-property relationships. Furthermore, comparison mechanical properties grade 316L stainless steel performed order evaluate if is competitive commercially available structural nanocrystalline state. A minority phase embedded face-centered cubic matrix could be observed multiple annealed states, as-received torsion processed material. For 200 h annealing at 500 °C, it determined that has hexagonal-closed-packed crystal structure. possible explanation for formation preferential segregation Co stacking faults.