Microstructure and Properties of Squeeze Casting AZ81E Magnesium Alloy after Solution Treatment

The effect of solution treatment on microstructure and properties of the squeeze casting AZ81E magnesium alloy was researched by optical microscope, X-ray diffraction, SEM and tensile tester. The results show that after solution treatment at 350-420 ℃, coarse and netlike β-Mg17Al12 phase dissolved gradually with the rise of solution temperature and extension of holding time. After solution at 400 ℃ for 8 h, the dendrite segregation had been effectively eliminated, RE phase became finner and was partly soluted to the base body. With the extension of holding time, hardness of the alloy decreased first and then rised. The minimum hardness of 59 HRE could be obtained when the holding time was 8 h. And the mechanical properties were improved significantly and at 400 ℃ the over-all properties were the best. After solution treatment, the tensile fracture mode at room temperature transformed from the mixture of quasi-cleavage fracture and ductile fracture to ductility transgranular fracture.