Improved mechanical properties of a near-eutectic high-entropy alloy via laser melting deposition

Abstract

The microstructure and mechanical properties of a dual-phase near-eutectic high-entropy alloy Al0.71CoCrFeNi (Al0.71) prepared by laser melting deposition (LMD) were investigated and compared with those of a single-phase FCC high-entropy alloy Al0.38CoCrFeNi (Al0.38). The Al0.71 consists of 65% FCC and 35% BCC phases, forming a near-eutectic microstructure that includes primary FCC dendrites with minor BCC precipitates, as well as a lamellar FCC-BCC eutectic microstructure. For Al0.71, the aluminum loss induced by evaporation during LMD process leads to a deviation from the intended eutectic composition. Both FCC and BCC phases in Al0.71 display chaotic grain orientations, which can be attributed to the microstructural heterogeneity of the alloy and the complex temperature field generated by the reciprocating scanning during LMD process. The Al0.71 achieved a desirable balance of strength and plasticity due to the synergetic strengthening effects of soft FCC phases and hard BCC phases.