New refractory high entropy alloys

Abstract

The paper presents researches on the microstructure and mechanical properties of a new types of refractory high entropy alloys, which can be used for thermal engine components as well as for military incendiary bullet. The main characteristics required for such applications are high compression resistance, microstructural stability during thermal stress, hardness and corrosion resistance. To obtain such specific characteristics, the raw materials must be melted in inert protective atmosphere, and then heat treated for the homogenization of the microstructure and chemical composition. In the paper, there have been studied three types of high entropy alloys, HfMoNiTaW, 2HfMoNi2Ta and MoNiTaW obtained in the vacuum arc remelting (VAR) equipment. The heat treatment, performed at 800 °C with a holding time of 4 hours, allows obtaining a good homogenization of the chemical composition while generating a decrease in the microhardness, from a maximum value of 637 HV0.2 to a minimum value of 527HV0.2.