Abstract:The present study systematically investigated the microstructural evolution and mechanical properties of MoNbVTa?.5 refractory high-entropy alloys (RHEAs) under varying annealing temperatures and holding times. It reveals that microstructural homogenization improves with increasing annealing temperature at a fixed 24 h of holding time. 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, 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 as-cast state.