镁合金中位错的高分辨Z衬度成像研究
Atomic-resolution Z-contrast imaging studies on dislocations in Mg alloys
查看参考文献28篇
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文摘
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利用Z衬度成像技术研究了两种耐热镁合金Mg_(97)Zn_1Y_2与Mg_(97)Zn_1Gd_2(at. %)中的位错。塑性变形过程中形成的倾侧晶界上周期性分布的基面〈a〉位错分解形成层错,伴随合金元素在层错上富集可以形成类似长周期堆垛的结构,能够钉扎晶界并抑制晶界高温软化。随着应变量增加,观察到了基面〈a〉位错与锥面〈c+ a〉位错构成的复合倾侧晶界,以及单纯由〈c+ a_(60)〉位错或〈c+ as〉位错重排构成的晶界,表明开动了〈c+ a〉锥面滑移系,有利于协调材料变形。合金元素在位错处偏聚形成柯垂尔气团,可以强化材料。热变形过程中Gd元素在Mg基体内位错的张应变区富集形成柯垂尔气团,加速β'-Mg_7Gd柱面析出相的异质形核生长。 |
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其他语种文摘
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Dislocations in two heat-resistant Mg alloys,Mg_(97) Zn_1Y_2 and Mg_(97) Zn_1Gd_2 (at. %),were studied using aberrationcorrected Z-contrast imaging techniques. Dissociation of basal〈a〉dislocations and associated segregation of solute atoms produced local structures like long-periodic stacking ordered phases at tilt GBs formed during plastic deformation,which may play an important role in both pinning the GBs and preventing them from softening at elevated temperatures. GBs composed of〈c+ a〉dislocations were formed due to the activation of pyramidal slip systems with increasing plastic strain. Pyramidal slip of〈c+ a〉dislocations is important for ductility of Mg alloys. Solute segregation along dislocations in the form of Cottrell atmospheres during hot deformation,not only plays an important role in strengthening by directly impeding dislocation motion,but also facilitates heterogeneous nucleation and growth of strengthening precipitates. These findings about dislocations provide insights on the strengthening and toughening mechanisms in Mg alloys. |
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来源
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电子显微学报
,2018,37(5):481-489 【扩展库】
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DOI
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10.3969/j.issn.1000-6281.2018.05.013
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关键词
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位错
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柯垂尔气团
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铃木偏聚
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析出形核
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像差校正电子显微学
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地址
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中国科学院金属研究所, 沈阳材料科学国家研究中心, 辽宁, 沈阳, 110016
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语种
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中文 |
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文献类型
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研究性论文 |
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ISSN
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1000-6281 |
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学科
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晶体学;金属学与金属工艺 |
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基金
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国家自然科学基金资助项目
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中国科学院前沿重点项目
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文献收藏号
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CSCD:6349817
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