The influence of temperature on twinning behavior of a Mg-Gd-Y alloy during hot compression

The microstructure evolution and plastic deformation mechanism of Mg-6.58Gd-5.7Y-0.55Zr alloy were investigated by uniaxial compression at temperatures ranging from 300 °C to 450 °C and with an initial strain rate of 0.1 s−1, and characterized by optical microscope (OM), scanning electron microscope (SEM) and electron back-scattering diffraction (EBSD). The effect of temperature on twinning behavior was focused in detail. At relatively low temperature, such as 300 °C, multiple twin variant pairs can be activated in one grain, and the twining process was dominated by nucleation. However, at high temperature, most of the twins activated in one grain belong to the single twin variant pair with the highest Schmid Factor (SF), and twin growth seems to represent the twinning behavior at 450 °C. The twinning behavior of Mg-6.58Gd-5.7Y-0.55Zr alloy at temperatures ranging from 300 °C to 450 °C basically follows Schmid law, and can be well understood in terms of variation of stress state and activated deformation modes with compression temperature.