热处理态MoNbVTa系难熔高熵合金的组织演化与力学性能

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

摘要:

通过调控热处理工艺，系统研究了不同退火温度与保温时间对MoNbVTa_0.5难熔高熵合金的微观组织与力学性能的影响规律。研究发现，退火时间为24 h时，随退火温度升高，合金组织均匀化程度提升。然而在1500 ℃以上退火时合金析出富(Nb, Ta)相，导致了合金塑性劣化。当退火温度为1400 ℃时，随保温时间的延长，合金屈服强度不断升高，而塑性应变因析出相的钉扎效应呈现先升后降趋势。1300 ℃/24 h均匀化退火后合金实现强度-塑性协同提升，屈服强度提高至1530 MPa，室温塑性变形量相比铸态时提高了58.6%，达到9.2%。

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.