Microcompression and cyclic deformation behaviors of coaxial copper bicrystals with a single twin boundary

This study reveals the extraordinary effect of an individual twin boundary (TB) on the mechanical behaviors of Cu bicrystals with a TB parallel to the loading axis whose primary slip vectors are always parallel to the TB plane. With direct experimental evidence, it is shown that there is no strengthening effect of the TB on the bicrystal under microcompression, and the TB is intrinsically strong enough to resist fatigue cracking with the slip bands becoming the preferential cracking sites finally.