Compression Deformation Mechanisms at the Nanoscale in Magnesium Single Crystal

The dominant deformation mode at low temperatures for magnesium and its alloys is generally regarded to be twinning because of the hcp crystal structure. More recently, the phenomenon of a loss of the twins has been reported in microcompression experiments of the magnesium single crystals. Molecular dynamics simulation of compression deformation shows that the pyramidal (a + c) slip dominates compression behavior at the nanoscale. No compression twins are observed at different temperatures at different loadings and boundary conditions. This is explained by the analyses, that is, the {10 (1) over bar2} and {10 (1) over bar1} twins can be activated under c-axis tension, while compression twins will not occur when the c/a ratio of the hcp metal is below root 3. Our theoretical and simulation results are consistent with recent microcompression experiments of the magnesium (0001) single crystals.