(华南理工大学 机械与汽车工程学院,广州 510640)
摘 要: 采用拉伸性能测试、定量金相分析、扫描电镜等手段研究挤压铸造Al-5.0Cu-0.6Mn-0.5Fe合金的显微组织和力学性能,分析挤压压力对合金的力学性能和显微组织的影响。结果表明:当挤压压力从0增大到75 MPa时,合金的抗拉强度(σb)和伸长率(δ)都显著增加。当挤压压力为75 MPa时,铸态合金的抗拉强度为298 MPa,伸长率达17.6%;经T5热处理后,合金的抗拉强度为395 MPa,伸长率为14.2%。当挤压压力从0增大到75 MPa时,α(Al)二次枝晶间距减小了69%,θ相(Al2Cu)和富Fe相的体积分数略有降低,针状β-Fe相消失,同时晶界处汉字状α-Fe相由连续的汉字状变成分散、细小的骨骼状。
关键字: 铝合金;挤压铸造;显微组织; 力学性能
(School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China)
Abstract:The microstructure and mechanical properties of Al-5.0Cu-0.6Mn-0.5Fe alloy prepared by squeeze casting were studied by tensile test, image analysis and scanning electron microscope. The effects of applied pressure on the microstructure and mechanical properties of the alloy were investigated. The results show that the ultimate tensile strength (σb) and elongation (δ) of the alloy increase significantly with increasing the applied pressure from 0 to 75 MPa. When the applied pressure is 75 MPa, the σb and δ of the alloy are 298 MPa and 17.6% in as-cast condition and 395 MPa and 14.2% after T5 heat treatment, respectively. When the applied pressure increases from 0 to 75 MPa, the second dendritic arm spacing of α(Al) decreases by 69%, the volume fractions of θ(Al2Cu) phase and the iron-rich intermetallic phases decrease slightly, the platelet β-Fe phases disappear, and the continuous Chinese script α-Fe phases at the grain boundary become more dispersive and smaller.
Key words: aluminum alloy; squeeze casting; microstructure; mechanical property