“…Crocker et al [16] predicted theoretically that a-U has 41 kinds of possible twinning modes based on the principle of minimum twinning shear and atomic shuffle. However, the operative twin modes relate to not only the intrinsic properties of material, such as crystal orientation [17,18] and grain size [19e22], but also the external conditions, such as temperature [17,23e26], pressure [27], strain rate [28e31] and etc.…”