The microstructure and mechanical properties of Mg-Gd-Y-Nd-Zr heat-resistant magnesium alloy were analyzed comparatively after deformation and T5 or T6treatment.During thermoplastic deformation process

dynamic recrystallization and dynamic precipitation can be taken place simultaneously.The dynamic precipitation can reduce the recrystallization nucleation driving force in the grain to prevent from occurrence of dynamic recrystallization partially.The comprehensive mechanical properties of the heat-resistant magnesium alloy with T5treatment（solid solution at 530 ℃ for 4h）are superior greatly to those of ones with T6treatment（solid solution at 530℃for 4h+aging treatment at 225℃for 16h）。Compared with T6 treatment

after T5 heat treatment

the tensile strength of the alloy is increased to 359.3 MPa

increased by approximately 48.5%

and elongation is increasing from 5.17%to6.5%.After peak ageing treatment

the main precipitation isβ′phase

which exhibits obvious pinning effect to grain boundary of the alloy

inhibiting the grain growth in long-time ageing condition.At the same time

secondary phase strengthening effects of precipitate phase take strength increase significantly.