摘要
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。
The microstructure was observed through optical microscope, electron microprobe and the variation of Vickers hardness with thermal exposure time has been also studied for mechanically alloyed (MA) Al-12Ti-6Nb exposed at 550℃ in air atmosphere The results show that the MA Al-12Ti-6Nb alloy manifests excellent thermal stability at 550℃ After the alloy is exposed for 200h at 550℃, the α-Ti cores trans form into Al 3 Ti nearly completely, and the primary cake-shaped Al 3 Ti becomes ellipsoidal The coarsening of Al 3 Ti particles was achieved through the α-Ti/Al 3 Ti phase boundary moving inward and the Al 3 Ti/Al phase boundary outward controlled by Ti and Al atoms diffusion through the surrounding Al 3 Ti band between α-Ti and Al matrix However, the flat Nb particles still stably exist with only a little increase in Al element within them The Vickers hardness doesn′t decrease for the alloy exposed for 50h at 550℃, and still retains nearly 90% of its primary values for the alloy exposed for 200h at 550℃
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
1997年第4期26-29,共4页
Rare Metal Materials and Engineering
关键词
机械合金化
组织
结构
热稳定性
铝合金
mechanical alloying, Al-12Ti-6Nb, microstructure, thermal stability
