Strength-ductility synergy of additively manufactured (CoCrNi)87Al13 medium entropy alloy with heterogeneous multiphase microstructure

In this study, a (CoCrNi)87Al13 medium-entropy alloy was fabricated by using laser-based directed energy deposition (L-DED). The yield strength and ultimate tensile strength of the (CoCrNi)87Al13 alloy were improved by 67% and 59%, respectively, compared with those of a L-DEDed CoCrNi alloy, and the ultimate elongation remained at 24%. A heterogeneous multiphase microstructure with multiscale ordered/disordered body-centered cubic phases was obtained by adding Al during the rapid solidification and thermal cycle history of the L-DED. The heterogeneous multiphase microstructure was closely correlated with the mechanical performance improvement, deformation, and fracture mechanisms of the alloys.