Orientation effect on / phase interface mediated deformation mechanism in titanium alloy

Ti alloys with dual alpha and beta phases are commonly used in various applications due to their superior mechanical properties. In the present work, to unravel the effect of orientation angle theta between the alpha and beta phases, molecular dynamics simulations were performed on Ti alloy bicrystal samples with the orientation angle varied from 0 to 90. Under compressive stress, the phase interface was observed to nucleate defects, leading to four distinct deformation mechanisms depending on the orientation angle. Prismatic < a > dislocations were identified at orientation angles around 0, while shear bands were observed in the range of 5(degrees) < theta < 35. Basal < a > dis-locations were present at 35 < theta < 70(degrees), and pyramidal II < c + a > dislocations were observed at 70(degrees) < theta < 90. The orientation-dependent variation of interface-mediated deformation mechanisms is explained by virtue of the critical resolved shear stress of each deformation mechanism and the Schmid factor on the corresponding slip system. Our findings provide insight into the role played by phase interfaces in determining the plastic deformation mechanisms of two-phase Ti alloys.