Dislocation Slip and Crack Nucleation Mechanism in Dual-Phase Microstructure of Titanium Alloys: A Review

The study on the deformation mechanism of titanium alloys is beneficial to revealing the influence of microstructure on mechanical properties, and then providing guidance for the optimization of microstructure and properties. For most near-alpha and alpha + beta titanium alloys, slip is the dominant deformation mechanism. Therefore, investigating the slip initiation and slip transfer behavior, as well as crack nucleation mechanism, is essential to reveal the fundamental relationship between microstructure and mechanical properties. However, due to the coexistence of grain boundary and phase boundary in dual-phase microstructure of titanium alloys, the phase content, grain size, grain boundary misorientation and alpha/beta orientation relationship would affect the slip initiation and transfer behavior, resulting in a very complex plastic deformation mechanism. Based on the previous investigations of deformation mechanism of near-alpha and alpha + beta titanium alloys, this review first analyzed the sequence of slip initiation between alpha and beta phases and discussed the main factors affecting the slip initiation in alpha phase. Secondly, the basic rule of slip transfer and the influence of different interfaces on slip transfer were reviewed. Finally, the mechanism of crack nucleation and effect of microstructure on crack nucleation were analyzed based on slip transfer behavior.