(華南理工大學(xué)機械與汽車工程學(xué)院，廣州 510640)
摘 要: 采用拉伸性能和硬度測試、光學(xué)顯微鏡、掃描電鏡和X射線衍射儀等手段研究不同Si含量對擠壓鑄造Al-5.0Cu-0.6Mn-0.7Fe合金顯微組織和力學(xué)性能的影響。結(jié)果表明：當擠壓壓力為0時，隨著Si含量的增加，凝固后期形成的富鐵相阻止液相補縮，形成縮松組織，導(dǎo)致合金的抗拉強度、屈服強度和伸長率都下降；當擠壓壓力為75MPa時，隨著Si含量增加，縮松組織消失，雖然細小和分散的α-Al15(FeMn)3(SiCu)2相和Al2Cu相數(shù)量增多，但Al6(FeMnCu)相消失，有利于晶界強化和阻止裂紋的擴展，使得合金的抗拉強度和屈服強度增加；雖然富鐵相數(shù)量的增加使得合金伸長率降低，但擠壓鑄造工藝減緩了伸長率降低的趨勢。當擠壓壓力為75 MPa和Si含量為1.1%(質(zhì)量分數(shù))時，合金的綜合力學(xué)性能最好，其抗拉強度為232 MPa，屈服強度為118 MPa，伸長率為12.4%。
關(guān)鍵字: Si; Al-Cu合金；擠壓鑄造；顯微組織；力學(xué)性能
（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
