Creep-Induced Phase Instability and Microstructure Evolution of a Nearly Lamellar Ti–45Al–8.5Nb–(W, B, Y) Alloy  

作　　者：Xuyang Wang Jieren Yang Rui Hu Zitong Gao Jinguang Li Hengzhi Fu 

机构地区：[1]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China [2]Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment,Northwestern Polytechnical University,Xi'an 710072,China

出　　处：《Acta Metallurgica Sinica(English Letters)》2020年第12期1591-1600,共10页金属学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51774238 and51971176);the 2018 Joint Foundation of Ministry of Education for Equipment Pre-research(No.6141A020332);the State Key Laboratory for Advanced Metal and Materials Foundation(No.2014-ZD06);the Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University(No.LZUMMM2020008)。

摘　　要：Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 and 900℃ under 150 MPa in air.Microstructures before and after creep tests were examined using scanning and transmission electron microscopy(SEM and TEM).Dislocations within the lamellar structure andβo(ω)region and twin intersection in massiveγgrains were investigated.Dislocation sliding played a critical role in the deformation ofωo phase,which preferentially occurred on the(0002)ωo plane.Possible deformation mechanisms were revealed.A stress-inducedγ→α2 phase transformation took place during the creep test at 850 and 900℃.α2 lamella could directly decompose into theωo phase at 850℃.The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix,thus could be detrimental to the creep properties.The correlations between creep properties and microstructure instability were discussed.

关 键 词：TiAl based alloy CREEP Microstructural stability Transmission electron microscopy(TEM) 

分 类 号：TG146.23[一般工业技术—材料科学与工程]