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与压铸Mg合金试样AZ91HP-F相比，压铸后经固溶处理的Mg合金AZ91HP-T4的硬度和屈服强度降低，延伸率、抗拉强度显著提高、抗拉强度与屈服强度比（σb／σ0.2）由压铸态的1.59上升至2.16．固溶处理后再经时效处理的Mg合金AZ91HP-T6的延伸率稍微降低．屈服强度和抗拉强度则显著提高，平均硬度值由压铸态的HB74上升至HB98．三种状态Mg合金的扫描电镜、X射线衍射和X射线能谱分析结果显示，AZ91HP中的主要第二相是固溶Zn的β－Al12Mg17相，这些相铸态时呈网状分布在α-Mg的固溶体晶界，固溶处理后溶入基体，时效过程中再次沿晶界析出，并形成片层胞状组织．β－Al12Mg17的溶解、析出和形态转变是Mg合金AZ91HP-T6时效强化的主要原因。
Compared with AZ91HP-F, the hardness and yield strength of AZ91HP-T4 Mg alloy after die casting decreased, the elongation and tensile strength significantly increased, and the ratio of tensile strength to yield strength (σb / σ0.2) increased from 1.59 in the as-cast state to 2.16. The elongation of the AZ91HP-T6 Mg alloy after aging treatment after solution treatment decreased slightly. Yield strength and tensile strength were significantly improved, the average hardness of HB74 from the as-cast rose to HB98. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy spectrum analysis of the three Mg alloys show that the main second phase in AZ91HP is the β-Al12Mg17 phase of Zn in solid solution, Mg solid solution grain boundaries, solution treatment into the matrix, the aging process again along the grain boundary precipitation, and the formation of lamellar cells. The dissolution, precipitation and morphological transformation of β-Al12Mg17 are the main reasons for the aging strengthening of AZ91HP-T6 alloy.