As–cast microstructures of HEA designed to be strengthened by HfC

Abstract

In this study, two new alloys, resulting of the addition of carbon and hafnium to a well–known high entropy alloy (HEA) – the equimolar CoNiFeMnCr one – to promote the formation of HfC carbides, were produced by conventional casting under inert atmosphere and characterized. The as–cast microstructures of the obtained HEA/HfC alloys were studied by X–ray diffraction, electron microscopy, energy dispersion spectrometry, and Vickers indentation. These HEA/HfC alloys are double–phased, with an austenitic matrix and interdendritic eutectic script–like HfC carbides. In terms of chemical composition and of crystallographic network, the matrix of the alloys is identical to the CoNiFeMnCr alloy. In that way, the two alloys can be considered as composite materials resulting of a HEA matrix strengthened by hard HfC particles.