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通过金相分析、XRD、SEM及TEM等分析手段,研究了AZ91D镁合金热处理状态下的相结构变化,结果表明:AZ91D镁合金在420℃固溶保温20 h,β-Mg17Al12几乎全部分解,Al原子以置换固溶的形式进入到Mg基体中;175℃时效保温不同的时间,随着时效保温时间的延长,析出相的析出方式和形态都发生变化。TEM观察发现,时效18 h的AZ91D镁合金中存在着短柱状的析出相,β-Mg17Al12与α-Mg之间存在着[011]β//[13 42]α的位向关系。
The phase structure of AZ91D magnesium alloy after heat treatment was studied by means of metallographic analysis, XRD, SEM and TEM. The results show that almost all of β-Mg17Al12 is decomposed, and Al The atoms enter into the Mg matrix in the form of substitutional solid solution. At different aging time of 175 ℃, the precipitation mode and morphology of precipitated phase change with the prolonging of holding time. TEM observation showed that short columnar precipitates existed in the AZ91D magnesium alloy aged for 18 h, and the orientation of [011] β // [13 42] α existed between β-Mg17Al12 and α-Mg.