Zr/Ta比对Zr-Ti-Nb-Ta难熔高熵合金微观组织及力学性能的影响

Effect of Zr/Ta Ratio on Microstructure and Mechanical Properties of Zr-Ti-Nb-Ta Refractory High-Entropy Alloys

摘要:

通过调控诱发原子尺寸与模量错配的合金组元，实现难熔高熵合金强度与延展性的最优组合，研究了Zr和Ta对Zr_45-xTi₁₅Nb₃₀Ta_10+x（x=0, 5, 10, at%）难熔高熵合金微观结构演变及室温力学性能的影响。结果表明：Zr/Ta比的变化未改变合金的相结构，3种合金的相组成均为单一的体心立方结构。但随着Zr/Ta比降低，合金的屈服强度与延展性同时提高，屈服强度从901 MPa增加至1003 MPa，延展性从13.3%提高至16.1%。延展性提升主要源于晶粒细化与晶格畸变减小；而强度增长则主要归因于高Ta含量引发的剪切模量失配增强与细晶强化之间的协同作用。本研究为成分变化对难熔高熵合金性能的影响提供了重要认识。

Abstract:

Optimal combination of strength and ductility for refractory high-entropy alloys (RHEAs) can be achieved by regulating the alloy composition that induces the mismatch between atomic size and modulus. Thus, the influence of Zr and Ta on the microstructure evolution and room-temperature mechanical properties of Zr_45-xTi₁₅Nb₃₀Ta_10+x (x=0, 5, and 10, at %) RHEAs was investigated. Results show that the variation in the Zr/Ta ratio does not change the phase composition of the alloys. All three alloys are only composed of body-centered cubic phase. However, with the decrease in Zr/Ta ratio, the yield strength and ductility of the alloys are increased simultaneously: the yield strength increases from 901 MPa to 1003 MPa, and the elongation increases from 13.3% to 16.1%. The enhancement in ductility is primarily caused by grain refinement and the decrease in lattice distortion. Meanwhile, the increase in yield strength is mainly attributed to the synergistic effect of the increased shear modulus mismatch induced by the higher Ta content and the grain refinement strengthening. This study provides valuable insights into the influence of composition variation on the properties of RHEAs.