Abstract: Twinning and martensitic transformations accommodate strain during plastic deformation of materials with hexagonal close packed crystal symmetry via the formation and growth of reoriented/transformed 3D domains. The kinetics of propagation of these domains is controlled by the intrinsic mobility of the facets/interfacial defects separating them from the host phase, by the internal stresses acting as driving forces for transformations to occur, and by the presence of local defects which can either impede or favor the propagation process. Naturally, transmission of twins across grain boundaries is suspected to play an important role in forming complex twin networks.
The material’s science community, surprisingly, has focused on twin and martensitic domain morphology and interface mobility mostly from a 2D perspective. This presentation will address the full 3D character of transformed domains and of their associated networks. Leveraging atomic and micron-scales characterization techniques in combination with both simulation and analysis tools, the aims are to unravel the nature of interfacial defects that mediate twinning and correlate their intrinsic properties (mobilities, metastable states) to the kinetics of microstructure evolutions. Among others, this presentation will discuss how twin networks form within complex microstructure via the activation of transmission events across grain boundaries. Critically, the work to be presented will demonstrate how twin transmission across grain boundaries differs from slip transmission; thereby leading to particularly complex and convoluted 3D networks of twins.