Selective laser melting of in-situ CoCrFeMnNi high entropy alloy: Effect of remelting

Abstract

In-situ multicomponent alloying in additive layer manufacturing shows inhomogeneous elemental distribution. This study aimed to minimize this inhomogeneity in equiatomic CoCrFeMnNi high entropy alloy (HEA) produced by selective laser melting (SLM) from a mixture of elemental powder. A detailed study was undertaken regarding the effects of remelting scan strategy on microstructural and mechanical properties, melt pool geometry, and elemental distribution of CoCrFeMnNi HEA manufactured using the SLM process. The SLM sample with remelting scan strategy showed a homogeneous elemental distribution. The remelted SLM sample showed a homogeneous hardness distribution. The X-ray diffraction of the as-built and remelted SLM showed a single-phase FCC structure, typical for a HEA. Prediction and observation of melt pool depth exhibited a lower depth in the remelted SLM samples. The microstructure of the melt pools of both as-built and remelted SLM showed a fine grain morphology, typical of rapid solidification. The boundary of melt pools in the as-built SLM and the inter-space of melt pools in the remelted SLM consisted of both coarse and equiaxed/columnar dendritic grains. The present results confirmed the possibility of fabricating a homogenized CoCrFeMnNi HEA from mixed elemental powders using SLM with remelting scan strategy.