| Structures and mechanical properties of Mg-Zn-Y alloys in the range of Y varied from 0.5% to 9% and Zn varied from 1.5% to 6% were researched; then the deformation mechanism of Mg-Zn-Y alloys were investigated; the change of the microstructure and the effect of theγ-ray to the wrought magnesium alloy AZ31 were primary discussed.The structure and performance of Mg-Zn-Y alloy with Y varied from 0.5% to 9% and Zn varied from 1.5% to 6% showed that when the Zn/Y (mass ratio) of alloy was low, main of the phases is transited from icosahedral quasicrystal I-phase reinforced in low Y alloys to I-phase coexists with W-phase. When the content of Y increased to 3% and the Zn/Y reached 1, I-phase disappeared and X-phase appeared; when the Zn/Y decreased lower than 0.5, the chief second phases were totally X-phase in high Y content alloys. In the Mg-Zn-Y alloys with low Y content (Y content is 0.5% and 1.5%) and Zn/Y exceeds 1, the second phases in alloys were distributed in the form of points then lines and finally spreading on the grain boundary, and the yield strength gradually increasing with Y content. For the alloys with the high Y (Y content is 3%, 6% and 9%), the main second phase is the 18R long period stacking ordered phase (LPSO) X-phase(Mg12ZnY) which lies on the grain boundary as needles that bind together. Mg-3%Zn-3%Y has the highest yield strength of 215MPa.All the failure of Mg-Zn-Y alloys was quasi-cleavage fracture.The deformation mechanism of Mg-Zn-Y alloys was investigated by TEM and EDX. In the low Y alloys, the yield strength and the plasticity of alloys are increasing; which is related to generated form of I-phase on the matrix. As I-phase coherent with matrix, it favors the deformation of the alloys. LPSO X-phase in high Y alloys decreases the stacking fault energy of Mg alloy from 200mJ to 4mJ, give rise to the dislocations on the (0001) plane spreading to stacking fault, and these dislocations on the basal plane are fixed and suppresses the basal and non-basal slip that operate predominantly in the plastic deformation of Mg alloy. This LPSO phase also prevents the growth of {10 1 2} deformation twin in Mg matrix. From the compare strengthen effort of I-phase and X-phase, it is found that X-phase has a better strengthen effort than I-phase.AZ31 wrought magnesium alloy will be refined more or less after tensile tests, but the grains are not uniform. With the increase of strain rate, the yield strength and the tensile strength of AZ31 alloy are all increasing, but the elongation is decrease. The effort ofγ-irradiation on deformation of AZ31 is investigated. Due to the point defects produced in the irradiation, AZ31 alloy gets irradiation damage; both tensile properties and plasticity are decreased. Irradiation lead to anisotropy of AZ31, the longitude is affected more than the cross section.
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