Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第18卷    第8期    总第113期    2008年8月

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文章编号:1004-0609(2008)08-1371-06
高应变速率冲击下2519A铝合金组织结构的转变
张新明,高志国,陈明安,李惠杰,刘 瑛,刘 波

(中南大学 材料科学与工程学院,长沙 410083)

摘 要:

采用分离式Hopkinson 压杆(SHPB)和Gleeble−1500热模拟装置对2519A-T87铝合金分别进行动态冲击和准静态实验,运用XRD和TEM对室温下应变率为0.001 /s和1 287~7 050 /s压缩冲击后试样的微观组织和相组成进行分析,利用小负荷硬度仪对冲击后试样进行显微硬度测试。结果表明:由外力功转化为相界面能和应变能可以补偿θ相形核功(∆G),导致试样受冲击后沉淀相θ′θ相发生转变并粗化,冲击变形应变率越高,冲击后试样硬度越低;随着冲击变形应变率上升,与基体共格或半共格的正方结构θ′相体积分数减小,与基体非共格体心正方结构θ相体积分数增加;减少材料受冲击后θ′相向θ相的转变数量可提高材料抗冲击性能。

 

关键词: 2519A铝合金;显微组织;转变;高应变速率;冲击

Microstructure transformation of 2519A aluminium alloy impacted at high strain rates
ZHANG Xin-ming, GAO Zhi-guo, CHEN Ming-an, LI Hui-jie, LIU Ying, LIU Bo

School of Materials Science and Engineering, Central South University, Changsha 410083, China

Abstract:2519A-T87 aluminum alloy was investigated in dynamic impact testing by split Hopkinson pressure bar (SHPB) and in quasistatic compression by Gleeble−1500 thermal simulation setup. The microstructures and phase compositions of compressed specimens subjected to dynamic impact testing at the strain rate range of 1 287−7 050 /s and quasistatic testing at the strain rate of 0.001 /s at room temperature were determined by TEM and XRD. The hardnesses of compressed specimens were measured by using little-duty Vickers hardness tester. The results show that the interface energy and strain energy due to external work can compensate the nucleation energy (∆G) of θ phase and lead to θ′ phase transforming into θ phase that coarsens gradually in the impacted specimen. The higher the strain rate, the lower the hardness of impacted specimens. With increasing strain rate the volume fraction of coherent or semi-coherent tetragonal θ′ phase decreases while the volume fraction of incoherent body centered tetragonal θ phase increases obviously. The most effective measure to promote the shock resistance of the alloy is to decrease the number density of θ phase evolving from θ′ phase in the impacted 2519A-T87 alloy.

 

Key words: 2519A aluminium alloy; microstructure; transformation; high strain rate; impact

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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