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中南大学学报(自然科学版)

Journal of Central South University

第48卷    第5期    总第273期    2017年5月

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文章编号:1672-7207(2017)05-1141-08
5A90铝锂合金的超塑性变形行为
王国玮1, 2,叶凌英1, 2,孙大翔1, 2,杨涛1, 2,陈敏1, 2,张新明1, 2

(1. 中南大学 轻合金研究院,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
)

摘 要: 采用光学显微镜、电子背散射衍射、电导率测试以及超塑性高温拉伸实验研究5A90铝锂合金超塑性变形行为和变形机理。研究结果表明:经450 ℃/30 min再结晶退火后,在变形温度为500 ℃、应变速率为8×10-4 s-1的超塑性变形条件下,可使伸长率由未退火状态的630%提升至1 120%;在超塑性变形过程中,晶粒由长条状逐渐变为等轴状,而退火后的晶粒更加细小且等轴化程度更高,再结晶退火还可以提高材料内部的空位浓度并增加大角度晶界所占的比例,这都有利于伸长率提高;在最适宜超塑性变形条件下,该材料的应变速率敏感性指数m为0.63,因此,其主要变形机制为晶界滑移,但在变形后期扩散机制成为一种协调机制。

 

关键词: 5A90铝锂合金;再结晶退火;超塑性;空位浓度;晶粒组织

Superplastic deformation behavior of 5A90 aluminum-lithium alloy
WANG Guowei1, 2, YE Lingying1, 2, SUN Daxiang1, 2, YANG Tao1, 2, CHEN Min1, 2, ZHANG Xinming1, 2

1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China

Abstract:The superplastic deformation behavior and deformation mechanism of 5A90 Al-Li alloy during superplastic deformation were studied by optical microscopy, electron back scattering diffraction, electrical conductivity test and high temperature tensile test. The results show that the elongation of the specimen which is recrystallized at 450 ℃ for 30 min before the tensile test can increase from 630% to 1 120% at an appropriate superplastic condition, which is obtained at temperature of 500 ℃ and an initial strain rate of 8×10-4 s-1. During the process of superplastic deformation, elongated grains gradually change to be equiaxed, and after annealing grain size becomes smaller and axis degree is higher. In addition, recrystallization annealing can improve vacancy concentration and increase the proportion of large angle grain boundary, which is beneficial to the improvement of the elongation. In the appropriate condition, the strain rate sensitivity index m of this material is 0.63, and the main deformation mechanism is GBS. But at the late stage of the deformation, diffusion is taken as a coordination mechanism.

 

Key words: 5A90 Al-Li alloy; recrystallization annealing; super plasticity; vacancy concentration; grain structure

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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