Microstructures and compositions of precipitated phases of Mg-4Al-1RE-xCa alloys before and after compressive creep were analyzed by optical microscope（OM）

scanning electron microscope（SEM）with energy dispersive spectrometer（EDS）and X-ray diffraction（XRD）

and the tensile properties and compressive creep behavior were also tested.The results show that the microstructure of as-cast AE41 alloy is characterized by classical dendrite

which is composed of coarseα-Mg matrix with un-even distribution and some acicular compound Al11Nd3 phase.As-cast microstructure is refined and skeletonshaped Al2 Ca phase and granulated Al2 Nd phase are increased gradually

while Al11Nd3 phase is decreased obviously with increasing in Ca addition.With the increase of Ca

yield strength and hardness of the alloys are improved

while the tensile strength and ductility of the alloy are decreases at ambient temperature.The strength is decreased and the plasticity is increased at high temperature

while elevated instantaneous tensile strength of the alloy is enhanced with the 0.8% Ca addition

where the value is138 MPa.Al2 Ca phase distributed along grain boundaries exhibits high thermal stability

which is beneficial for the improvement of the creep resistance.However

the mechanical properties are deteriorated significantly with formation of closed network of Al2 Ca phase.