论文部分内容阅读
Phase field simulations incorporating contributions from chemical free energy and anisotropic interfacial energy are presented for the β→α transformation in Ti-6Al-4 V alloy to investigate the growth mechanism ofα lamellae of various morphologies from undercooled β matrix.The α colony close to realistic microstructure was generated by coupling the Thermo-Calc thermodynamic parameters of α and β phases with the phase field governing equations.The simulations show that α lamellar side branches with feathery morphology can form under a certain combination of interfacial energy anisotropy and temperature.α lamellae 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 kx: ky was set as 0.1: 0.6.Besides,higher interfacial energy anisotropy can accelerate the formation of α lamellae,and the equilibrium shape of α lamellae changes from rod to plate as the interface energy anisotropy ratio kx∶ ky vary from 0.1∶ 0A to 0.1∶ 0.8 under 820 ℃.Experiments were conducted to study the α lamellar side branches in Ti-6Al-4 V (Ti-6.01Al-3.98 V,wt.％) and Ti-4211 (Ti-4.02Al-2.52V-1.54Mo-1.03Fe,wt.％) alloys with lamellar microstructure.Electron backscatter diffraction (EBSD) results show that α lamellar side branches and their related lamellae share the same orientation.The predicted temperature range for α lamellar side branches formation under various interfacial energy anisotropy is consistent with experimental results.