Interaction between slip and [formula omitted] tensile twinning in Zr alloy: Quasi in situ electron backscatter diffraction study under uniaxial tensile test

Abstract

In this study, a technique that allows electron backscatter diffraction (EBSD) observation in the same point of interest under uniaxial tensile testing, i.e., a quasi in situ EBSD analysis technique, was developed and performed to investigate the interaction between slip and {101¯2} tensile twinning in a Zr alloy. Both the slip-independent and slip-assisted {101¯2} twins were investigated. The former twin is formed when the global stress surpassed the required critical stress, and the latter one is formed due to the local stress concentration near the grain boundary accumulated in the soft-oriented adjacent grain, although the global stress remains insufficient to activate the twinning. The formation of a slip-independent or slip-assisted {101¯2} twin seems to be closely linked to the crystal orientation relative to the loading direction. It is due to the bimodal basal texture exhibited in the present alloy that the slip-assisted twins can be observed. Furthermore, compared to slip-independent twins, the slip-assisted twinning is more likely to form at a higher strain, because substantial strain accumulation is essential to trigger its activation.