Development of high strength high plasticity refractory high entropy alloy based on Mo element optimization and advanced forming process

Refractory high entropy alloy is a potential substitute material for high temperature structures because of its excellent mechanical properties of high temperature resistance. In this paper, three kinds of refractory high-entropy alloys, M0, M10 and M20, were designed by adjusting the content of Mo element and formed by Laser powder bed melting(LPBF) technology. The solidification thermodynamics, microstructure and mechanical properties of the three kinds of alloys were analyzed. The effect of Mo content on the microstructure and mechanical properties of the three kinds of alloys was studied. With the increase of Mo element content, the grain size of the alloy becomes smaller and smaller, the yield strength increases greatly, and the plasticity of the alloy decreases continuously. The compressive yield strength of high strength M20 alloy is up to 1285 MPa, the ultimate strength is 2447 MPa, and the elongation is 27%. The high plasticity M0 alloy exhibits compressive superplasticity. The tensile yield strength and ultimate strength of M10 alloy are 1184 MPa and 1403 MPa, and the elongation is 5.1%. In this paper, the matching problem between plasticity and strength of refractory high-entropy alloys at room temperature is solved by combining alloy composition optimization and LPBF forming technology, which lays a foundation for the industrial application of refractory high-entropy alloys.