High-Temperature Phase Transformations in Multicomponent Fecocrnival Alloy

Abstract

The phase transformations proceeding in real time in as-cast high-entropy FeCoCrNiVAl alloy are studied using high-temperature in situ X-ray diffraction in a helium atmosphere at 293–1273 K. In initial state, this alloy is a single-phase BCC solid solution ordered according to B2 type. It is found for the first time that a tetragonal σ-phase of CrFe type forms at 1073 K on the surface of the alloy. The surface layer of the σ-phase is ~22 µm in thickness. The influence of annealing on changes in phase composition of the high-entropy alloy is analyzed. Microstructure of the alloy is studied using scanning electron and optical microscopy. The microhardness and effective Young’s modulus of the high-entropy alloy are determined at room temperature.