Effect of subfreezing testing temperature on tensile mechanical behavior of fine-grained magnesium

The effect of testing temperature on mechanical properties and deformation mechanisms was investigated by tensile testing of fine-grained magnesium samples under a range of temperatures (i.e. room temperature 20 °C, subfreezing temperatures 0 °C, −30 °C, and −60 °C) and microstructural observations of both untested and tested samples using electron backscatter diffraction. The results suggest that mechanical properties and deformation mechanisms were significantly affected by the variation of testing temperature. Strength increased linearly and ductility decreased linearly with the decrease of testing temperature. Although twinning is generally known to be athermal, this experimental study shows that tensile twinning is the dominating deformation mechanism at room temperature, and that twinning is negligible and dislocation operation is the primary deformation mechanism at 0 °C, −30 °C, and −60 °C.