Significant Improvement the Mechanical Properties of CoCrNi Alloy by Tailoring a Dual FCC-Phase Structure

Abstract

In this work, SixCoCrNi (x = 0, 0.1, 0.2, 0.3, 0.4, molar ratio) alloys were designed by introducing elemental Si into CoCrNi, a medium-entropy alloy (MEA). The effects of Si addition on the microstructure and mechanical properties of the as-cast SiCoCrNi alloys were investigated. The results suggested that a novel Si-rich face-centred cubic (FCC) phase formed in the Si0.3CoCrNi and Si0.4CoCrNi alloys. The Si-rich FCC phase, which featured high hardness and was located between the dendrites of the matrix FCC phase (with higher phase fraction), significantly increased the yield strength of the Si0.4CoCrNi alloys five times compared with the CoCrNi alloy.