Nanoscale study of cyclic deformation behaviour and mechanism of annealing twin

Abstract

Atomic force microscopy (AFM) and orientation imaging microscope (OIM) have been used to study the cyclic deformation of annealing twin. It found the existence of intrinsic deformation mechanism basing on the findings on the nanoscale. The slips on the planes intersecting and parallel to twin boundaries (TBs) lead to the formation of the unique chevron shapes “∧” and “∨” (consisting of the slopes on two sides of the TB) in the areas of twin's two opposite TBs, which makes a regular zigzag shape “/ \\ /” or “\\ / \\”. The tilting angle of the slope increased with cycle number increasing in the initial stage, but some decreased due to deformation hardening whereas others continued increasing after certain cycles. The tilting angle of slope changes on the different sites along a long TB.