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ＡＺ９１ＨＰ压铸试样在加热至 ４１５ ℃、保温 ８ ｈ并淬火之后，晶界上离异共晶的粗块状β－Ａｌ１２Ｍｇ１７相将溶入基体，形成过饱和的α－Ｍｇ固溶体α－Ｍｇ固溶体在人工时效过程中，将发生β－ Ａｌ１２Ｍｇ１７的非连续和连续的沉淀析出。非连续析出的β－Ａｌ１２Ｍｇ１７相在时间和数量上分别先于和大于连续析出的β－Ａｌ１２Ｍｇ１７相，其形态和数量都随时效时间变化，对合金的性能影响较大。金相组织观察显示，非连续析出的β－Ａｌ１２Ｍｇ１７相首先在晶界形核，开始时呈颗粒状，随后进入块和胞状共存阶段，最后块状的β－Ａｌ１２Ｍｇ１７相消失，胞状β－Ａｌ１２Ｍｇ１７相不断地向晶内蔓延长大。伴随着β－Ａｌ１２Ｍｇ１７相的析出与形态转变过程，ＡＺ９１ＨＰ性能也随之变化，显示了明显的时效硬化特征。
The AZ91HP die-cast sample was heated to 415 ℃ for 8 h and quenched. The coarse-grained β-Al12Mg17 phase on the grain boundary dissolved into the matrix to form a supersaturated α-Mg solid solution. During aging, non-continuous and continuous precipitation of [beta] -Al12Mg17 will occur. The non-continuous precipitation of β-Al12Mg17 phase in time and amount respectively before and more than the continuous precipitation of β-Al12Mg17 phase, its morphology and the number of aging time changes with great influence on the performance of the alloy. The microstructure observation showed that the discontinuous precipitated β-Al12Mg17 phase first nucleated in the grain boundary and began to be granular, and then entered into the phase of block and cell-like coexistence. Finally, the massive β-Al12Mg17 phase disappeared and the cellular β-Al12Mg17 phase Constantly spread to the crystal growth. Along with the precipitation and morphological transformation of β-Al12Mg17 phase, the properties of AZ91HP also change, which shows the obvious characteristics of age-hardening.