High Strength and Ductility of an Additively Manufactured Crconi Medium-Entropy Alloy Achieved by Minor Mo Doping

Selective laser melting (SLM) of a (CoCrNi)95Mo5 medium-entropy alloy (MEA) is explored to architect the dislocation-formed sub-grains and ultrafine μ precipitates. The high strength and ductility were achieved in the as-SLMed (CoCrNi)95Mo5 alloy, where the yield strength, ultimate tensile strength (UTS) and fracture strain were ~0.79 GPa, ~0.97 GPa and 35.9%, respectively. These excellent mechanical properties mainly originated from the hierarchical microstructures being composed of high-density dislocations-formed equiaxed cellular structures, low-angle grain boundaries (LAGBs) within the columnar cellular structures, fine (Mo, Cr)-enriched μ precipitates, and the lattice defects (i.e. dislocations, stacking faults and Lomer-Cottrell locks). In addition, the formation of low-density semi-coherent μ nanoprecipitates also enhanced the strengthening and minimized the loss of ductility in the (CoCrNi)95Mo5 MEA