The effects of thermal-cold cycling treatment on microstructures and properties of electromagnetic stirred AZ91 magnesium alloy were analyzed.The electromagnetic stirred AZ91 magnesium alloy was subjected to deep cryogenic treatment at different time after solution treatment

and the same aging treatment was performed.The results reveal that after the deep cryogenic treatment

the tensile strength and elongation of the alloy are improved

and the grain is refined compared with those of the solution samples.In addition

the precipitation of the second phase particles occurs in the cryogenic process.The tensile strength and elongation of the alloy reach 214 MPa

8.95%

respectively

after the cryogenic treatment for 24 h.The deep cryogenic treatment alloy was carried out the aging treatment for 1 h

where the tensile strength of the alloy is significantly improved to 242 MPa.