GPa grade cryogenic strength yet ductile high-entropy alloys prepared by powder metallurgy

Abstract

The carbon-doped Fe50Mn30Co10Cr10 HEAs with excellent cryogenic mechanical properties were prepared by powder metallurgy, and their tensile deformation behavior and strain-hardening mechanism were investigated. The yield strength of the HEAs at 77 K improved from 489.7 to 1087.0 MPa as the carbon content increased from 0 to 3 at. %, which mainly stems from the increased lattice friction caused by the addition of carbon and the cryogenic environment; the ultimate tensile strength of the HEAs doped with 2 and 3 at. % carbon reached 1.2 and 1.4 GPa, respectively, while the elongation to fracture reached 31.6 % and 16.8 %, respectively, which is mainly attributed to the joint activation of microbands, twinning, and HCP phase. The deformation mechanism gradually changed from deformation-induced phase transformation to microbands and twinning with increasing carbon content under cryogenic conditions. This study provides a meaningful reference for the design and development of powder metallurgy HEAs with excellent performance in cryogenic applications.