Fabrication, microstructure and mechanical property of a novel Nb-rich refractory high-entropy alloy strengthened by in-situ formation of dispersoids

Abstract We fabricated Nb 42 Mo 20 Ti 13 Cr 12 V 12 Ta 1 , a novel refractory high-entropy alloy (RHEA) enriched with niobium (Nb), by following a high-energy ball milling and spark plasma sintering (SPS) method. The microstructure of the bulk RHEA formed a single body-centered cubic (BCC) matrix with in-situ-formed carbide dispersoids. The combination of the effect of the severe deformations caused by the milling, the short sintering time, and the impedance of the grain growth caused by the dispersoids led to the formation of nano-sized grains, in spite of the high sintering temperature of 1200 °C. This resulted in outstanding mechanical properties. The bulk Nb 42 Mo 20 Ti 13 Cr 12 V 12 Ta 1 RHEA exhibits a compressive yield strength of 2680 MPa, a maximum strength of 3896 MPa, and a Vickers hardness of 741 HV. The excellent mechanical properties of the alloy can be attributed to the strengthening of the dispersion and the solid solution, coupled with the grain refinement effects.