As the deformation proceeded to fracture, the surface morphology at 77K was quite different from that at 293K. Clearly, the numerous activated and interlaced slip bands at 293K (Fig. 7(c)) mainly arose fromtheinteriorofthegrains,indicatingthatthetensiledeformationof the alloy mainly occurred inside the grains. However, fewer slip bands started in the inner grains with more visible grain boundary (Fig. 7(d)). This showed that the formation of slip bands was much easier at 293K with localized cross-slip bands [33]. Moreover, wider and sharper roughness zones appearing on the grain boundary (Fig. 7(d)) were involved in the larger tensile strain at 77K (Fig. 3(a))