论文部分内容阅读
将机械合金化（ＭＡ）Ａｌ－１２Ｔｉ－６Ｎｂ合金在５５０℃下空气中长时间暴露后，用光学显微镜和电子探针对其组织结构变化进行了观察与分析，测定了维氏硬度。结果表明，ＭＡＡｌ－１２Ｔｉ－６Ｎｂ表现出良好的热稳定性。在５５０℃下暴露２００ｈ后，Ａｌ３Ｔｉ中的亚稳的α－Ｔｉ核才全部转变为Ａｌ３Ｔｉ，Ａｌ３Ｔｉ颗粒随之粗化，饼状的Ａｌ３Ｔｉ变成椭球体；Ａｌ３Ｔｉ颗粒的粗化是通过Ｔｉ、Ａｌ原子扩散所控制的α－Ｔｉ／Ａｌ３Ｔｉ相界内缩和Ａｌ３Ｔｉ／Ａｌ相界外扩实现的；片状Ｎｂ则仍稳定存在，未有Ａｌ３Ｎｂ生成。合金暴露５０ｈ维氏硬度不降低，暴露２００ｈ后，硬度仍维持在原始硬度的９０％左右。
After the mechanical alloying (MA) Al-12Ti-6Nb alloy was exposed to air at 550 ℃ for a long time, its microstructure and structure were observed and analyzed by optical microscope and electron probe. Vickers hardness was measured. The results show that MAAl-12Ti-6Nb shows good thermal stability. After exposure at 550 ℃ for 200h, the metastable α-Ti nuclei in Al3Ti all transformed into Al3Ti, the Al3Ti particles coarsen and the cake-like Al3Ti became ellipsoid. The coarsening of Al3Ti particles was achieved by Ti, Al Al-Ti / Al3Ti phase boundary shrinkage and Al3Ti / Al phase boundary diffusion controlled by atomic diffusion. Tabular Nb is still stable without Al3Nb formation. The Vickers hardness of the alloy exposed 50h does not decrease, the hardness remains at about 90% of the original hardness after 200h exposure.