Microstructure evolution, mechanical properties and strengthening mechanism of refractory high-entropy alloy matrix composites with addition of TaC

Abstract

This study focuses on novel refractory MoNbRe0.5W(TaC)x high-entropy alloy matrix composites synthesized by vacuum arc melting. The microstructure evolution, compressive mechanical properties at room temperature and strengthening mechanism of the composites with addition of TaC are analyzed and discussed. The MoNbRe0.5W(TaC)x composites consist of a BCC solid solution as the matrix and an eutectic microstructure (BCC and multi-component carbide (Mo, Nb, W, Ta)C phases) at grain boundaries. The lamellar eutectic structure would be formed from the decomposition of subcarbide (Mo, Nb, W, Ta)2C and the fully solid solubility of Re. The MoNbRe0.5W(TaC)0.5 composite has the maximum failure strain of 10.25%. The MoNbRe0.5W(TaC)0.5 to MoNbRe0.5W(TaC)0.6 composites exhibit excellent comprehensive mechanical properties, with excellent strength and reasonable ductility at room temperature. The reinforcement mechanism of the composites is dominated by precipitation and fine-grained strengthening effect. The good ductility of MoNbRe0.5W(TaC)0.5 composite is contributed to the grain refinement of the BCC matrix phase.