Effect of solid solution and aging heat treatment on microstructure and mechanical properties of Mg-Nd-Zr alloy were investigated by optical microscope

scanning electron microscopy and hardness tester.The results show that with the increase of solution temperature and holding time

compounds in the grain boundaries are dissolved gradually when the alloy is treated at 460℃to 520℃.When the solution temperature is too high and the holding time is too long

grain is grown up.With the increase of aging time

the solution residual phase is dissolved gradually

and the second phase is precipitated homogeneously

so the alloy hardness is increasesd after solid solution at 490℃for 8h.The second phase is coarsened as a result of over-aging

which leads to the decrease of hardness.After 490℃×8hsolid solution treatment and 225 ℃ ×4haging treatment

the Mg-Nd-Zr alloy has the desirable mechanical properties.