热处理对铸造Ti-23Al-17Nb合金组织和拉伸性能的影响

Effect of heat treatment on microstructure and tensile properties of cast Ti-23Al-17Nb alloy

在1000℃和1020℃对铸造合金保温3 h后空冷,研究不同热处理温度对铸造Ti-23Al-17Nb(摩尔分数,%)合金组织和拉伸性能的影响。结果表明:铸造合金为等轴晶,晶界和晶粒内均析出呈网篮状魏氏组织的α_2板条;经热处理后,晶粒内细小的α_2板条充分析出,晶界处连续的α_2相断开;随着处理温度的提高,析出的α_2板条数量随之减少,板条宽度随之增加;热处理能提高合金的抗拉强度和伸长率,经1020℃,3 h,AC热处理后试样的伸长率达到4%,其拉伸断口主要是由沿晶断裂和准解理断裂组成。

The cast alloy was insulated at 1 000 and 1 020 ℃ for 3 h and then air-cooled. The effect of heat treatment temperature on the microstructure and tensile properties of cast Ti-23Al-17Nb （mole fraction, %） alloy were investigated. The results show that the macrostructure of the cast alloy is equiaxed grain. The lath α2 phase precipitated in the alloy exhibits a fine basket weave Widmanstatten microstructure. After heat treatment, the α2 phase precipitates more than the cast alloy, and the α2 phase in boundary is disconnected. With the increase of temperature, the quantity of the α2 phase decreases, but its width increases. Heat treatment can improve the tensile strength and elongation of the alloy. After heat treatment at 1 020 ℃ for 3 h, AC, the elongation of sample reaches 4%. The tensile fracture consists of intergranular fracture and cleavage fracture.