Hot deformation behavior and dynamic precipitation characteristics of Mg-Gd-Nd(-Sm)-Zr alloys

We deeply analyze the deformation behavior of Mg-Gd-Nd(-Sm)-Zr alloys under high temperature uniaxial compression, and explore the influence mechanism of Sm on the microstructure evolution of Mg-Gd-Nd-Zr alloy. We can draw the following conclusions: the addition of Sm delays the dynamic recrystallization of Mg-Gd-Nd-Zr alloy, resulting in the increase of stress and the decrease of machinability. There is no dynamic precipitation in Mg-Gd-Nd-Zr alloy at 400 °C/0.01 s−1/0.7, which is related to the high solute-vacancy binding energy of Nd. Under the same deformation condition, two kinds of dynamic precipitates with different size and shape appear in Mg-Gd-Nd-Sm-Zr alloy: fine particle phase and coarse lamellar phase. The two precipitates are Mg(Gd, Nd, Sm) with body-centered cubic structure, and are incoherent with the matrix. The coarse lamellar phase effectively hinders dislocation rearrangement, which explains the delay of dynamic recrystallization.