Promoting columnar-to-equiaxed transition in AlCoCrFeNi high entropy alloy during selective laser melting by adding Cr3C2

Abstract

The 5 at% Cr3C2 particles were mixed with AlCoCrFeNi high entropy alloy powder particles and then selectively laser melted. The addition caused full columnar-to-equiaxed grain transition (CET) and significant grain refinement. The inter-dendritic regions and grain boundaries (GBs) of the as-fabricated sample were segregated with Cr and C, which led to the formation of an FCC belt/network structure along GBs. The grain interior was dominated by BCC/B2 and sporadically decorated by Cr7C3 particles. The partitioning of Cr and C into liquid ahead of the solidification front, which may have generated significant constitutional supercooling, is believed to be responsible for the full CET.