5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

γ-TiAl alloys are regarded as promising candidates in aero and automobile industry due to their superior properties including low density, high specific strength, excellent oxidation resistance and creep strength. However, the application of these alloys is limited by the problems such as micro-segregations, inhomogeneous microstructure, texture and severe cracking tendency. In the article, the effect of thermal cycling in the mushy zone and solidification rates on the microstructure of Ti-48Al-2Cr-2Nb alloy and Ti-45Al-8.5Nb-(W,B,Y) alloy were firstly discussed. Then, the phase transformation behaviors and microstructure evolution of Ti-45Al-8.5Nb-(W,B,Y) alloy was investigated. And based on phase transition sequence, a novel multi-step isothermal treatment (TIT) during solidification process was proposed to control the microstructure of Ti-45Al-8.5Nb-(W,B,Y) alloy and the influence of TIT on lamellar structure, homogeneity, texture and cracking was analyzed.