In-situ investigation on the β to α phase transformation in Ti-45Al-8.5Nb-(W, B, Y) alloy

In this work, an in-situ observation of β to α phase transformation in Ti-45Al-8.5Nb-(W, B, Y) (at. %) alloy was conducted using high-temperature laser-scanning confocal microscopy (HTLSCM). The results show that the nucleation of α grain occurs at β grain boundaries or on borides. The morphology of the α phase is strongly dependent on the cooling rate. On fast cooling, α phase presents a lath-like Widmannstätten morphology, whereas the equiaxed ones form at slow cooling. Electron backscatter diffraction (EBSD) results show that the volume fraction of Burgers α phase decreases with cooling rate reducing. These phenomena can be attributed to the competitive growth mechanism between the textured and non-Burgers α phase during β to α transformation.