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25卷    第11期    总第200期    2015年11月

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文章编号:1004-0609(2015)-11-3040-11
Si含量对挤压铸造Al-5.0Cu-0.6Mn-0.7Fe合金显微组织和力学性能的影响
赵愈亮,孟凡生,张杨,张大童,杨超,张卫文

(华南理工大学机械与汽车工程学院,广州 510640)

摘 要: 采用拉伸性能和硬度测试、光学显微镜、扫描电镜和X射线衍射仪等手段研究不同Si含量对挤压铸造Al-5.0Cu-0.6Mn-0.7Fe合金显微组织和力学性能的影响。结果表明:当挤压压力为0时,随着Si含量的增加,凝固后期形成的富铁相阻止液相补缩,形成缩松组织,导致合金的抗拉强度、屈服强度和伸长率都下降;当挤压压力为75MPa时,随着Si含量增加,缩松组织消失,虽然细小和分散的α-Al15(FeMn)3(SiCu)2相和Al2Cu相数量增多,但Al6(FeMnCu)相消失,有利于晶界强化和阻止裂纹的扩展,使得合金的抗拉强度和屈服强度增加;虽然富铁相数量的增加使得合金伸长率降低,但挤压铸造工艺减缓了伸长率降低的趋势。当挤压压力为75 MPa和Si含量为1.1%(质量分数)时,合金的综合力学性能最好,其抗拉强度为232 MPa,屈服强度为118 MPa,伸长率为12.4%。

 

关键字: Si; Al-Cu合金;挤压铸造;显微组织;力学性能

Effect of Si content on microstructures and mechanical properties of Al-5.0Cu-0.6Mn-0.7Fe alloy prepared by squeeze casting
ZHAO Yu-liang, MENG Fan-sheng, ZHANG Yang, ZHANG Da-tong, YANG Chao, ZHANG Wei-wen

School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China

Abstract:The effect of Si content on the microstructures and mechanical properties of Al-5.0Cu-0.6Mn-0.7Fe alloy prepared by squeeze casting was studied by tensile and hardness test, optical microscopy, scanning electron microscopy and X-ray diffraction. The results show that the ultimate tensile strength, yield strength and elongation of the alloy decrease with the increase of Si content when the extrusion pressure is 0 because the Fe-rich intermetallic prevents liquid feeding and forms shrinkage in the late solidification. The ultimate tensile strength and yield strength of the alloy increase with the increase of Si content when the extrusion pressure is 75 MPa because the shrinkage disappears and promotes the formation of small and scattered α-Al15(FeMn)3(SiCu)2 and Al2Cu phase, and inhibits formation of Al6(FeMnCu) phase which favors for the grain boundary strengthening and prevents the crack propagation. However, the elongation decreases with the increase of Fe-rich intermetallics amount, while the squeeze casting slows the decreasing trend. When the applied pressure is 75MPa and the Si mass fraction is 1.1%, the mechanical properties of the alloy are the best, the tensile strength is 232 MPa, the yield strength is 118 MPa and the elongation is 12.4%.

 

Key words: Si; aluminum alloy; squeeze casting; microstructure; mechanical property

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

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

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