Electron microscopy investigation on deformation-twin/precipitates interaction structures in an AZ91 alloy
曹志坚 1刘林林 1孙鹏阳 1黄子坤 1刘翠秀 1孙威1
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作者信息
1. 北京工业大学固体微结构与性能北京市重点实验室,材料与制造学部,北京 100124
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摘要
本文综合利用透射电子显微镜(transmission electron microscopy,TEM)及高分辨透射电子显微镜(high resolution transmission electron microscope,HRTEM)电子显微表征技术,对冲击变形时效AZ91镁合金中变形孪晶与β-Mg17Al12析出相交互作用引发的变形结构进行了观察和表征.结果表明:(1)β析出相阻碍{ 10(1)2｝孪晶生长使其界面形成台阶结构导致孪晶板条呈现粗细不均的形貌,更严重的交互作用可导致孪晶界发生大角度弯折,同时诱发基体中扭折带的形成以协调孪晶变形;(2){ 10(1)1}孪晶与β析出相的交互作用会产生局域应力集中,导致连锁诱发{ 10(1)2}孪晶形核,表明孪晶与析出相的交互作用可以促进孪晶形核.
Abstract
In this paper,the deformation microstructures induced by the interaction of different types of twins with β-Mg17Al12 precipitates(β-phase)in shock-loaded AZ91 magnesium alloy was investigated by a combination of transmission electron microscope(TEM)and high resolution transmission electron microscope(HRTEM)techniques.The results show that:(1)the growth of { 10(1)2}twins can be hindered by β-phases,and this will result in forming step structure at twin boundaries,such that twin laths appear to have uneven morphology.More severe twin/precipitate interaction can allow a twin boundary to be bent to a large angle with local kinking occurring to accommodate the local stress concentration.(2)The interaction between { 10(1)1 } twin and β precipitates can produce local stress concentration of high degree,to result in nucleation of {10(1)2} twins in sequence,indicating that the interaction between twins and precipitates can promote the nucleation twinning.
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