Microstructural Evolution and Mechanical Properties of Heat-Treated MoNbVTa Refractory High Entropy Alloy

Abstract:

The microstructural evolution and mechanical properties of MoNbVTa_0.5 refractory high-entropy alloy (RHEA) under varying annealing temperatures and holding time were investigated. The results show that microstructural homogenization improves with the increase in annealing temperature at a fixed holding time of 24 h. However, annealing above 1500 °C induces the precipitation of (Nb,Ta)-rich phases, which deteriorates ductility. At 1400 °C, prolonged holding time enhances yield strength, while plastic strain initially increases and then decreases due to the pinning effect of precipitated phases. Notably, the RHEA after homogenization annealing at 1300 °C for 24 h achieves a synergistic improvement in strength and plasticity: the yield strength increases to 1530 MPa, and plastic deformation reaches 9.2%, representing a 58.6% enhancement compared to the RHEA at as-cast state.