Transmission of mechanical twins across grain boundaries in Mg is a mechanism that can facilitate intergranular crack propagation by providing a path to cracks along along the twin interface. Clearly, understanding twin transmission requires us to understand twin growth. Traditionally, both mechanisms have been characterized as 2D processes, defined by the ‘forward’ twin shear direction , and the direction normal to the coherent twin boundary. Our recent 3D studies of twin domain interfaces reveal anisotropic mobility and a relative easiness of lateral twin propagation along , and point to the need for regarding twins as 3D growing domains in order to fully understand their behavior. As a consequence, it is natural to wonder what is the role of both, the forward and the lateral motion of the twin, concerning transmission across grain boundaries.
In this talk we review the most recent experimental and modeling information related to twin transmission across grain boundaries and discuss new results associated with the lateral motion. In brief, we examine experimental and computational results from: (1) statistical EBSD analysis of twin sections and (2) Phase Field and 3D Molecular Dynamic simulations of twins reacting with grain boundaries.