Anisotropic deformation induced by spherical indentation of pure Mg single crystals

A spherical indenter was impressed on low index planes in pure Mg single crystals and the resulting deformation structures such as slip bands and twins around and beneath each indentation were investigated. Indentations on (11¯00) and (112¯0) showed crystallographic anisotropy and elliptical morphology, which differed greatly from the indentations on (0001). Many twins occurred around and beneath (11¯00) and (112¯0) indentations, all of which were identified to be {101¯2} type. In addition, the twin regions were dependent on crystal orientation. Distributions of activated deformation modes under the indentation tests were estimated using a crystal plasticity finite element method. Numerical results of (0001) indentation found that basal and pyramidal-2 slips were axisymmetrically distributed, while the distributions of basal slip and twin regions were anisotropic according to calculated results of (11¯00) and (112¯0) indentations. The results of these calculations suggest that the anisotropy of strain components induced by the basal slip leads to the anisotropic development of the twin region.