Slip initiation in interlayered β and corresponding slip transfer during compression of a lamellar-structure titanium alloy
Ke Wang, Zhibing Yan, Yu Zhou, Shizhong Wei, Xiaodong Wang, Renlong Xin, Qing Liu
Abstract
The scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) were used for a quasi in-situ observation on the slip trace and crystallographic orientation at four strains during the compression of a widmannstätten-structure α/β titanium alloy. The previous investigations suggested that the slip always initiated in lamellar α prior to interlayered β due to the lower yield strength and higher Young's modulus of HCP α phase. Interestingly, it is found that the slip initiates in the interlayered β prior to lamellar α within the α colony in this work. Meanwhile, the preferential slip initiation in interlayered β does not occur at the highest Schmid factor (SF) which is calculated by the applied stress. The preferential slip in interlayered β is related to the heterogeneous deformation among different α colonies, which is related to the distribution of deflection angle θ between loading direction and c-axis of α phase. The slip transfers from interlayered β to lamellar α indirectly, which not only requires a good collaboration between SF and geometric compatability parameter (m'), but also needs a large accumulation of deformation in interlayered β.