Twinning-Associated Boundaries in Hexagonal Close-Packed Metals

In this article, we highlighted twinning-associated boundaries that play crucial roles in nucleation, growth, and interactions of deformation twins. According to microscopic characterizations and atomistic simulations in Mg, three types of boundaries are reviewed, including (I) prismatic-basal boundaries associated with twin nucleation via pure-shuffle mechanism, (II) serrated coherent twin boundaries associated with twin growth and shrinkage via glide and climb of twinning dislocations, and (III) tilt prismatic-prismatic and basal-basal boundaries associated with co-zone twin-twin interactions. More importantly, these boundaries affect twinning and detwinning processes that may correspond to twinning-induced hardening and seem universally associated with twins in hexagonal close-packed metals.