(華南理工大學(xué) 機(jī)械與汽車工程學(xué)院，廣州 510640)
摘 要: 研究在不同擠壓力下凝固的Al-Si-Cu-T4的顯微組織和力學(xué)性能。結(jié)果表明：在擠壓力下凝固時(shí)，該合金顯微組織發(fā)生明顯變化，其抗拉強(qiáng)度和伸長率均有明顯提高。當(dāng)擠壓力為0.1~50 MPa時(shí)，隨著擠壓力的增加，初生α(Al)晶粒尺寸和共晶Si粒子長寬比均顯著減小，Si相形貌由長針狀變成粒狀或圓棒狀。同時(shí)，枝晶間距減小，Al2Cu相量和枝晶間孔洞數(shù)量減少，力學(xué)性能提高；而當(dāng)擠壓力為50~100 MPa時(shí)，擠壓力的增加對合金顯微組織和力學(xué)性能影響不大。因此，50 MPa為該合金的合適擠壓力，在該條件下凝固的合金經(jīng)T4熱處理后，其抗拉強(qiáng)度和伸長率分別為323.6 MPa和8.51%。此外，分析討論了不同擠壓力下凝固的合金斷口裂紋的形成。
關(guān)鍵字: Al-Si-Cu合金；擠壓鑄造；力學(xué)性能；微觀組織
Al-Si-Cu-T4 solidified at different squeeze pressures
（School of Mechanical and Automotive Engineering, South China University of Technology,
Guangzhou 510640, China）
Abstract: Microstructures and mechanical properties of Al-Si-Cu-T4 solidified at different squeeze pressures were investigated. The results show that at the pressures applied during solidification, the microstructures of the alloy change significantly, and both tensile strength and elongation of the alloy are improved remarkably. When the squeeze pressure increases from 0.1 MPa to 50 MP, the size of primary α(Al) and aspect ratio of eutectic Si phase are decreased evidently and the morphology of eutectic Si particles is changed from long acicular to small granular, and the dendrite arm spacing, content of Al2Cu phase and porosities between dendrites are decreased, while the mechanical properties are increased. When the squeeze pressure increases from 50 MPa to 100 MPa, the microstructure and mechanical properties of the investigated alloy show little variation. It is indicated that the proper squeeze pressure of the investigated alloy is 50 MPa at which the tensile strength and elongation reach to 323.6 MPa and 8.51%, respectively, after solution heat treatment. Furthermore, the crack origin of the investigated alloys solidified at different squeeze pressures was analyzed and discussed.
Key words: Al-Si-Cu alloy; squeeze casting; mechanical property; microstructure
