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 degrees C, and transformed into a face-centered cubic phase above 500 degrees C. The as-milled powder was subsequently consolidated by spark plasma sintering at 900 degrees 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. (C) 2013 Elsevier B. V. All rights reserved.