Semi-solid isothermal heat treatment is thought to be a potential method for the manufacturing of magnesium alloys slurry with nondendritic structure. The present work investigates the microstructure and the compression deformation behaviour of AZ91D magnesium alloy following semi-solid isothermal heat treatment. The research results indicate that

after treated at 570 ℃ for 60 min

the dendritic structure of AZ91D alloy becomes unobvious. In addition

with the compression strain increasing the semi-solid compression stress of AZ91D alloy treated at 570 ℃ for 60 min rapidly reaches a maximium value when the compression strain is about 0.025

then the compression stress gradually decreases and finally kept a constant stress level. Furthermore

with the deformation temperature or rate increasing

the semi-solid compression stress of AZ91D alloy treated at 57 0℃ for 60 min decreases and increases

respectively.