时效处理对稀土钪微合金化钛合金组织与性能的影响

为提高钛合金在高温下的服役寿命,开展了稀土钪微合金化钛合金材料高温蠕变试验研究。将Ti64-0.25Si-xSc(x=0,0.3)合金在950 ℃×0.5 h,AC固溶后,分别在不同的温度和时间下时效,对合金的维氏硬度和高温抗蠕变性能进行测试,将蠕变曲线按时间硬化蠕变模型ε=Aσⁿt^m拟合,借助OM、TEM表征分析合金的微观组织演变。结果表明,合金在510 ℃下时效6 h的蠕变性能最为优异,加入稀土钪可以抑制晶粒的长大,改变晶粒的取向,促进网篮组织的形成,在合金中形成的Sc₂O₃可以净化基体,对提高钛合金的高温抗蠕变性能有着明显的作用。合金微观结构中存在大量的位错相互作用,堆积缠绕,合金的蠕变机制主要是位错的滑移。

Effect of aging on microstructure and properties of rare earth Sc microalloyed titanium alloy

In order to improve the service life of titanium alloys at high temperatures, experimental research on high temperature creep of rare-earth scandium microalloyed titanium alloy materials was carried out. The Ti64-0.25Si-xSc (x=0, 0.3) alloys were aged at different temperatures for different time after solid solution treatment (950 ℃×0.5 h, AC), then the Vickers hardness and high temperature creep properties of the alloys were tested, the creep curves were fitted to a time hardening creep model ε=Aσⁿt^m, and the microstructure of the alloys were analyzed by OM and TEM. The results show that the creep properties of the alloys are the best when aged at 510 ℃ for 6 h, for the scandium addition can inhibit the grain growth, change the grain orientation distribution, and promote the formation of basket-weave structure; and the formation of Sc₂O₃ in the alloy can purify the matrix, which has a significant effect on improving the high temperature creep performance of the alloys. There are a large number of dislocation interaction, stacking and entanglement in the alloy microstructure, and the creep mechanism of the alloy is mainly the slip of dislocation.