Plastic deformation behavior and mechanism of bismuth single crystals in principal axes

Tensile tests of single-crystal bismuth were performed for the a₁-axis [21-1-0], a2-axis [121-0] and c-axis [0001]. The mechanism of the a₁-axis and a₂-axis plastic deformation at 298 K is twinning deformation at the initial deformation stage. Subsequent plastic deformation mechanism is the slip deformation that occurs by the changes in the crystallographic orientation inside twin crystals that is advantageous to the slip. The mechanism of the c-axis plastic deformation at 298 K is slip deformation, where the secondary slip system becomes activated. On the other hand, the slip deformation is the primary deformation mechanism and twinning deformation is not observed for any axes at 423 K.