时效对新型Ti-Al-V中熵合金组织性能的影响

采用真空悬浮熔炼法制备出新型Ti-Al-V中熵合金,使用全自动密度天平测定合金密度,并对其分别在500 ℃和700 ℃下时效处理2 h,利用光学显微镜、扫描电镜、X射线衍射仪和维氏显微硬度计研究时效温度对其显微组织、物相组成及力学性能的影响。结果表明:Ti-Al-V中熵合金是一种轻质(密度4.18 g/cm³)、高硬度(铸态505 HV)新型合金;铸态和时效后的合金中均存在BCC结构的基体和HCP结构的富Ti板条状/粒状/针状析出相两种相结构;时效处理的合金中析出相数量相比铸态明显增加,并且时效温度提高,粒状/针状形貌的析出相数量进一步增加;铸态时合金的硬度较高,但力学性能均匀性差,随着时效温度的升高,合金硬度逐渐降低,但力学性能相对更均匀。

Effect of aging on microstructure and properties of a new type of Ti-Al-V medium-entropy alloy

A new type of Ti-Al-V medium-entropy alloy was prepared by vacuum suspension smelting, and aged at 500 ℃ and 700 ℃ respectively for 2 h. The density of the alloy was determined by using a fully automatic density balance. The effect of aging temperature on microstructure, phase composition and mechanical properties of the alloy was investigated by metallographic microscope, scanning electron microscope, X-ray diffractometer, and Vickers microhardness tester. The results show that the Ti-Al-V medium-entropy alloy is a new type of alloy with light weight (density of 4.18 g/cm³) and high hardness (as-cast of 505 HV), in which BCC matrix and HCP Ti-rich lamellar/granular/acicular precipitates are found in both as-cast and aged states. The amount of precipitated phases in the aged alloy is significantly increased compared with that in as-cast state, and with the increase of aging temperature, the amount of precipitated phases with granular/needle morphologies further increases. The hardness of the alloy is higher in the as-cast state, but the uniformity of the mechanical properties is poor. As the aging temperature increases, the hardness of the alloy gradually decreases, but the mechanical properties are relatively more uniform.