Microstructure instability of fully lamellar TiAl alloy containing high content of Nb after long-term thermal cycling

作     者：方璐 丁贤飞 何建平 张来启 林志 林均品 Lu FANG;Xian-fei DING;Jian-ping HE;Lai-qi ZHANG;Zhi LIN;Jun-pin LIN

作者机构：北京科技大学 新金属材料国家重点实验室北京100083 北京科技大学 国家材料服役安全科学中心北京100083 

出 版 物：《Transactions of Nonferrous Metals Society of China》 (中国有色金属学报（英文版）)

年 卷 期：2014年第24卷第10期

页      面：3095-3102页

核心收录：

学科分类：0806[工学-冶金工程] 08[工学] 0818[工学-地质资源与地质工程] 0815[工学-水利工程] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0813[工学-建筑学] 0703[理学-化学] 0814[工学-土木工程] 0702[理学-物理学] 

基　　金：Project(2011CB605500)supported by National Basic Research Program of China Project(51171015)supported by National Natural Science Foundation of China Project(2012M520166)supported by China Postdoctoral Science Foundation Project(2012Z-06)supported by State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,China Project(FRF-TP-12-164A)supported by Fundamental Research Funds for the Central Universities of China 

主　　题：TiAl alloys thermal cycling thermal stability discontinuous coarsening 

摘      要：Microstructure instabilities of the fully lamellar Ti-45Al-8.5Nb-（W,B,Y） alloy were investigated by SEM and TEM after long-term thermal cycling（500 and 1000 thermal cycles） at 900 °C. Two major categories of microstructure instability were produced in the alloy after the thermal cycling： 1） The discontinuous coarsening implies that grain boundary migrations are inclined to occur in the Al-segregation region after the long-term thermal cycling, especially after 1000 thermal cycles. Al-segregation can be reduced during the process of long-term thermal cycling as a result of element diffusion; 2） The α2 lamellae become thinner and are broken after 1000 thermal cycles caused by the dissolution of α2 lamellae through phase transformation of α2→γ. The γ grains nucleate within the α2 lamellae or（α2＋γ） lamellae in a random direction.