Formation mechanism of α lamellae during β→α transformation in polycrystalline dual-phase Ti alloys  

作　　者：Jia Sun Min Qi Jinhu Zhang Xuexiong Li Hao Wang Yingjie Ma Dongsheng Xu Jiafeng Lei Rui Yang 

机构地区：[1]Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [2]University of Shanghai for Science and Technology,Shanghai 200093,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]School of Materials Science and Engineering,University of Science and Technology of China,Hefei 230026,China

出　　处：《Journal of Materials Science & Technology》2021年第12期98-108,共11页材料科学技术（英文版）

基　　金：financially supported by the National Key Research and Development Program of China(No.2016YFB0701304);the Natural Science Foundation of China(Nos.51671195 and51871225);the Chinese Academy of Sciences(Nos.QYZDJ-SSWJSC031-01,XDC01040100 and XXH13506-304)。

摘　　要：Phase field simulations incorporating contributions from chemical free energy and anisotropic interfacial energy are presented for theβ→αtransformation in Ti-6 Al-4 V alloy to investigate the growth mechanism ofαlamellae of various morphologies from undercooledβmatrix.Theαcolony close to realistic microstructure was generated by coupling the Thermo-Calc thermodynamic parameters ofαandβphases with the phase field governing equations.The simulations show thatαlamellar side branches with feathery morphology can form under a certain combination of interfacial energy anisotropy and temperature.αlamellae tend to grow slowly at high heat treatment temperature and become wider and thicker as temperature increase from 800 to 900℃provided that the interfacial energy anisotropy ratio k_(x):k_(y) was set as 0.1:0.6.Besides,higher interfacial energy anisotropy can accelerate the formation ofαlamellae,and the equilibrium shape ofαlamellae changes from rod to plate as the interface energy anisotropy ratio k_(x):k_(y) vary from 0.1:0.4 to 0.1:0.8 under 820℃.Experiments were conducted to study theαlamellar side branches in Ti-6 Al-4 V(Ti-6.01 Al-3.98 V,wt.%)and Ti-4211(Ti-4.02 A1-2.52 V-1.54 Mo-1.03 Fe,wt.%)alloys with lamellar micro structure.Electron backscatter diffraction(EBSD)re sults show thatαlamellar side branches and their related lamellae share the same orientation.The predicted temperature range forαlamellar side branches fo rmation under various interfacial energy anisotropy is consistent with experimental results.

关 键 词：αLamellae Side branches TI-6AL-4V Interfacial energy anisotropy Phase field model 

分 类 号：TG146.23[一般工业技术—材料科学与工程]