Columnar to equiaxed transition in additively manufactured CoCrFeMnNi high entropy alloy

Abstract

Here, a single-track CoCrFeMnNi high entropy alloy（HEA） was prepared by laser melting deposition. The microstructural evolution of columnar to equiaxed transition was experimentally observed across the molten pool. The temperature gradient and solidification rate were theoretically calculated by a finite element model via numerical simulation. Combining experimental observations and numerical simulations, a solidification map was established to quantitatively reveal the underlying correlation between solidification parameters and microstructural morphology. A decrease in the ratio of gradient temperature to solidification rate corresponding to an increasing constitutional undercooling induced columnar to equation transition during the laser melting deposition process. It was expected that the fundamental understanding of microstructural prediction of single-track as-deposited HEA parts via the solidification map would have implications on the production of bulk components with the desired microstructure and high performance.