AZ91镁铝合金中HCP/BCC相界面结构

Structure of HCP/BCC interphase boundaries in AZ91 Mg-Al alloy

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 (0 0 0 2 ) 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 (0 110 ) α∥ (330 ) 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。

The HCP/BCC interphase boundaries between the Mg matrix and γ Mg 17 Al 12 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 (0110) α ∥(330) 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.