Microstructure and deformation mechanism of 0 0 0 1 magnesium single crystal subjected to quasistatic and high-strain-rate compressiveloadings

Abstract

0001 magnesium single crystal samples were mechanically tested under compressive loadings at a quasistatic strain rate (0.001s−1) and a dynamic strain rate (1000s−1), respectively. The tested samples were then investigated through various microstructural characterization techniques. Dynamic loading led to much higher maximum strength and larger strain hardening rate than quasistatic loading for the tested material. The microstructure features were clearly different from each other for the two loading conditions, which indicated that the deformation mechanisms for the quasistatic testing were different from those for the dynamic testing. The microstructure analysis showed that (a)prismatic and secondary pyramidal dislocation operations happened in the samples under quasistatic loading and dynamic loading, while tension twinning and tension–compression double twinning also happened in the sample under quasistatic loading; (b)the sample under high-strain-rate dynamic loading remained as single crystal, while that under quasistatic loading was refined to become polycrystalline; and (c)twinning operations under quasistatic loading led to grain refinement.