Formation of large scaled zero-strain deformation twins in coarse-grained copper

Most deformation twins in nanocrystalline metals were reported to produce zero macroscopic strain via either random activation of partials or cooperative slip of three partials. In their coarse-grained counterparts, deformation twins produce a net macroscopic strain and change the grain shape since a twin forms via the glide of a single twinning partial dislocation on successive {111} planes driven by Peach-Koehler force. Here, we report the formation of large scaled zero-macrostrain deformation twins in coarse-grained copper with medium stacking fault energy. The responsible formation mechanism is proposed and its effect on twinning or detwinning processes is discussed.

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