Mechanical Properties and Shear Localization of High Entropy Alloy CoCrFeMnNi Prepared by Powder Metallurgy

摘要

Mechanical properties of the CoCrFeMnNi high entropy alloy at strain rates (1 × 10~(-4) s~(-1) to 0.1 s~(-1) and 1 × 10~3 s~(-1) to 3 × 10~3 s~(-1)) and at temperatures (298.15, 673.15 and 1073.15 K) are investigated. Hat shaped specimens are used to induce the formation of an adiabatic shear band under controlled shock-loading tests. Results indicate that the yield strength of the CoCrFeMnNi high entropy alloy is increasing sensitively with increasing the strain rates. Grains in the boundary of the shear band in the CoCrFeMnNi high entropy alloy are highly elongated along the shear direction, and the core of the shear band consists of nanotwins and ultrafine equiaxed grains. Rotational dynamic recrystallization takes effects on the formation of the microstructures in the shear band.