(1. 华南理工大学 机械工程学院，广州 510641;
2. Department of Materials Engineering,
Monash University, Clayton,
Victoria 3168, Australia)
摘 要: 采用常规和高分辨电镜研究了时效AZ91镁铝合金中2种形态γ-Mg17Al12析出相的HCP/BCC相界面结构。 发现第一类析出相的惯习面 (0002)α ∥{330}γ以及与其对接的另外2组主要晶面的面间错配度都很小（4%和2%）， 因此界面能较小； 而第2类析出相的惯习面 (011-0)α∥(3-30)γ以及与其对接的另一组主要晶面的面间错配度都较大（11% 和15%）， 因此界面能较大。 从界面能和相变应变两方面讨论了各类析出相析出密度差别的原因, 提出了改变析出密度、 提高镁铝合金时效强化效果的可能途径。
关键字: AZ91镁铝合金； γ-Mg17Al12析出相； HCP/BCC相界面； 透射电镜分析
（1. College of Mechanical Engineering,
South China University of Technology, Guangzhou 510641, China;
2. Department of Materials Engineering,
Monash University, Clayton,Victoria 3168,Australia）
Abstract:The HCP/BCC interphase boundaries between the Mg matrix and γ-Mg17Al12 precipitates for two kinds of precipitates produced in an aged AZ91 Mg-Al alloy were characterized using both conventional and high resolution TEM. It is found that the planar misfit across the (0002)α∥{330}γ habit plane of the first kind of precipitate is very low(<4%), thus forming a low (strain) energy interface, while that across the (011-0)α∥(3-30)γ habit plane of the second kind of precipitate is markedly high(15%), thus producing a high (strain) energy interface. The difference in precipitation density of various kinds of precipitate was interpretted in terms of the interfacial energy, and of the strain induced by the precipitation; and plausible ways of altering the relative densities of the precipitates so as to enhance the precipitation-strengthening effect of the alloy were proposed.
Key words: AZ91 Mg-Al alloy; γ-Mg17Al12 precipitate; HCP/BCC interphase boundary; TEM
