Effect of low-temperature aging on microstructure and mechanical properties of AZ81-4%Gd magnesium alloy

To investigate the effect of low-temperature aging on the microstructure and mechanical properties of AZ81-4%Gd magnesium alloy,the aging treatment at 150 ℃ with different holding time after solid solution treatment was performed.The microstructures and mechanical properties of the alloy were analyzed and tested with x-ray diffractometer(XRD),scanning electron microscope(SEM),energy disperse spectroscopy(EDS) and hardness tester.In addition,the reasons for the change in both microstructures and properties of the alloy were analyzed with metallography theory.The results show that during the low-temperature aging treatment of the alloy,β-Mg17Al12 phases are precipitated in both continuous and discontinuous ways.And the morphologies of two kinds of β-Mg17Al12 phases are different.The analysis shows that the precipitation mode and morphologies of β phases are related to the mechanism of nucleation and growth.Under the testing conditions used in this investigation,the hardness of the alloy gradually increases with increasing the aging time.