AZ91镁合金中变形孪晶与析出相交互作用结构的电子显微学研究

AZ91镁合金中变形孪晶与析出相交互作用结构的电子显微学研究

曹志坚，刘林林，孙鹏阳，黄子坤，刘翠秀，孙  威^*

（北京工业大学固体微结构与性能研究所，北京100124）

摘  要  本文综合利用TEM及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{ 101(—)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) { 101(—)2 }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{ 101(—)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。

关键词 AZ91镁合金；变形孪晶；析出相；交互作用；电子显微技术

中图分类号：TG146.2⁺2；TG115.21⁺5.3  文献标识码：A  doi:10.3969/j.issn.1000-6281.2024.01.005

Electron microscopy investigation on the interaction structure of deformation-twin and precipitates in an AZ91 alloy

CAO Zhi-jian，LIU Lin-lin，SUN Peng-yang，HUANG Zi-kun，LIU Cui-xiu，SUN Wei*

(Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124, China)

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 transmission electron microscope (TEM). The results show that the growth of { 101(—)2} twins can be hindered by β-phases. The step structure was formed at the twin boundaries, resulting in uneven morphologies of twin laths. The higher interaction between twin and precipitate further leaded to the twin boundary to be bent to a large angle with local kinking occurring to accommodate the local stress concentration. In addition, the interaction between {101(—)2 } twin and β precipitates generated the local stress concentration, inducing the nucleation of{101(—)2 } twins, indicating that the interaction between twins and precipitates can promote the nucleation twinning.

Keywords   magnesium alloy；deformation twins；precipitated phase；interaction, electron microscopy

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