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中南大学学报(自然科学版)

Journal of Central South University

第49卷    第12期    总第292期    2018年12月

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文章编号:1672-7207(2018)12-2931-08
7B04铝合金超塑性变形的组织演变与变形机理
廖荣跃1, 2, 3,叶凌英1, 2, 3,陈明安1, 2, 3,杨栋1, 2, 3,孙泉1, 2, 3

(1. 中南大学 材料科学与工程学院,湖南 长沙,410083;
2. 中南大学 有色金属材料科学与工程教育部重点实验室,湖南 长沙,410083;
3. 中南大学 有色金属先进结构材料与协同创新中心,湖南 长沙,410083
)

摘 要: 采用高温拉伸、电子背散射衍射、扫描电镜和透射电镜研究7B04铝合金超塑性变形的组织演变过程,利用聚焦离子束技术定量计算各变形机制的贡献量。研究结果表明:在变形初始阶段,扩散蠕变引起物质迁移的作用逐渐增强,不存在明显的晶内位错滑移,促使物质在垂直拉伸方向的晶界附近堆积,形成无沉淀析出带,条纹带在试样表层的晶界附近形成;在试样真应变由0.23增至0.43的过程中,晶界滑移对整个变形的贡献量由45.81%增大至52.34%,主要变形机制为伴随扩散蠕变的晶界滑移机制;当继续变形至真应变为1.26时,楔形和圆形空洞同时出现,继续拉伸时空洞扩展,部分跨过空洞的晶须被拉长直至断裂,最终垂直于拉伸方向的空洞发生聚合或连接,试样沿该部位断裂。

 

关键词: 7B04铝合金;超塑性;聚焦离子束;晶界滑移;扩散蠕变

Microstructure evolution and deformation mechanism of 7B04 aluminum alloy under superplastic deformation
LIAO Rongyue1, 2, 3, YE Lingying1, 2, 3, CHEN Mingan1, 2, 3, YANG Dong1, 2, 3, SUN Quan1, 2, 3

1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,
Central South University, Changsha 410083, China

Abstract:The superplastic deformation behavior and deformation mechanism of 7B04 aluminum alloy during superplastic deformation were studied by high temperature tensile test, electron back scattering diffraction(EBSD), scanning electron microscope(SEM) and transmission electron microscope(TEM), and the contribution of each deformation mechanism was calculated by focused ion beams(FIB). The results show that material migration caused by diffusion creep stack near the grain boundary perpendicular to the tensile direction at the initial stage and precipitation-free zones exists. In addition, stripe bands appear on the sample surface. In the process that the true strain of the sample increases from 0.23 to 0.43, the contribution of grain boundary sliding to the total deformation increases from 45.81% to 52.34%. The main superplastic mechanism of 7B04 aluminum alloy is grain boundary sliding accompanied diffusion creep without the participating of intragranular dislocation slipping. The wedges and circular cavities appear when the true strain is 1.26.With the proceeding of deformation, the cavities holes stretch and part of the whiskers across the cavities elongate until fracture. Finally, the sample is broken as a result of aggregation or connection of the cavities perpendicular to the tensile direction.

 

Key words: 7B04 aluminum alloy; superplasticity; focused ion beams; grain boundary sliding; diffusion creep

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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