Powder Synthesis and Characterization of Al_0.5CoCrFeNi High-Entropy Alloy for Additive Manufacturing Prepared by the Plasma Rotating Electrode Process

Abstract

The Al 0.5 CoCrFeNi high-entropy alloy powder was produced by using a plasma rotating electrode process. The morphology, microstructure, and physical properties of the powder were characterized. The powder exhibited a smooth surface and a narrow particle size distribution with a single peak. The relationships between particle size and secondary dendrite arm space as well as cooling rate were evaluated as follows: λ = 0.0105d + 0.062 and v c = 4.34 × 10 −5 d −2 + 2.62 × 10 −2 d −3/2 , respectively. The Al 0.5 CoCrFeNi powder mainly consisted of fcc + bcc phases. As the powder particle size decreased, the microstructure of the powder changed from dendritic to columnar or equiaxed, along with a decrease in the fcc content and an increase in the bcc content. The tap density (4.76 g cm −3 ), flowability (15.01 s × 50 g −1 ), oxygen content (<300 ppm), and sphericity (>94%) of the powder indicated suitability for additive manufacturing.