Mechanical alloying synthesis and spark plasma sintering consolidation of CoCrFeNiAl high-entropy alloy

An equiatomic CoCrFeNiAl high-entropy alloy was synthesized by mechanical alloying, and phase evolutions, microstructure, thermal properties and annealing behaviors were investigated. It was found that a body-centered cubic structured solid solution with refined microstructure of 20 nm in grain size could be obtained after 30 h milling. As-milled powder exhibited good phase stability until 500 °C, and transformed into a face-centered cubic phase above 500 °C. The as-milled powder was subsequently consolidated by spark plasma sintering at 900 °C. BCC phase and FCC phase coexisted in the consolidated HEA, which had excellent properties in Vickers hardness of 625 HV and compressive strength of 1907 MPa.