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 Alloys

摘要:

本文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下MoNbVTa0.5难熔高熵合金微观组织与力学性能的演化规律。研究发现,退火时间为24h时,随退火温度的升高,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,劣化了合金塑性。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钉扎效应呈现先升后降趋势。1300℃下24h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1530MPa,室温塑性变形量达9.2%,相比铸态时提高了58.6%。

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.