With different solution temperature and holding time

the microstructure evolution and microhardness of AZ91D magnesium alloys containing SiC particles were investigated.The results show that the continuous net-likeβphase in initial as-cast ingot disappears gradually with the increase of solution temperature

accompanying with the fragmentation of Mg2Si phase with Chinese script morphology

and spheroidization rate is increased.The grain boundary becomes distinct with the solution temperature of 400 ℃.With solid solution treatment at 400 ℃ for 16h

the unstableβphase is almost dissolved into the matrix phase and the spheroidization of Mg2Si phase exhibits desirable.However

the change of morphology of Al8Mn5 phase can not be observed due to its high decomposition temperature.After solid solution at 400 ℃ for 20h

the spheroidization trend is weakened and the primary grain is coarsened greatly.The value of micro-hardness is decreased continuously as a result of the disappearance ofβphase and spheroidization of Mg2Si phase

while a slight increase of the micro-hardness for the sample at 400℃ for 16h can be observed due to solution strengthening.