The anisotropy of deformation twinning in bcc materials: Mechanical loading, temperature effect, and twin-twin interaction

By integrating atomistic simulations with theoretical calculations, we investigate the prevalence of {112} deformation twins in bcc materials and their sensitivity to the loading direction as well as temperature. Our atomistic simulations reveal the copious occurrence of {112} twins involving either hcp or fcc intermediate phases. The hcp and fcc cases occur in bcc titanium alloy during [100] compression and tension, respectively. Similarly, they can also manifest in bcc iron under different temperature conditions. Furthermore, by calculating the correspondence matrix, we identify the fcc and hcp cases as the normal deformation twin mode and the 1/2 atoms -shuffle mode, respectively. The twinning modes have a significant influence on twin-twin interactions and the final microstructure. Our theoretical calculation confirms that the selection of specific twin modes and twin variants is governed by the correlation between their deformation path and mechanical loading. The results underscore the crucial role of mechanical loading and temperature in activating the specific twin modes, thereby providing a novel avenue for engineering twin microstructures through carefully designed thermomechanical processing techniques.