Sr/P变质处理对挤压铸造Al-17.5Si合金组织与性能的影响
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摘要
研究Sr和P变质对挤压铸造Al-17.5Si合金组织与力学性能的影响。试验结果显示:挤压铸造对过共晶Al-17.5Si合金的组织产生了显著的影响,共晶组织明显细化,初生Si相的数量减少并细化,同时力学性能显著提高。Sr变质后的Al-17.5Si合金在压力下凝固,共晶Si相进一步细化,变为十分细小的纤维状,合金的抗拉强度和伸长率比重力铸造分别提高了59%和328.7%。当P变质处理Al-17.5Si合金挤压铸造成形后,合金组织中却出现了大量的粗大初生Si相颗粒,使得合金的力学性能呈现了降低的趋势。由此确定,挤压铸造过共晶Al-Si合金的最佳变质处理为Sr变质,P变质不适用于挤压铸造成形的过共晶Al-Si合金。
The effects of Sr and P modification on the microstructure and mechanical properties of the Al-17.5 Si alloy were mainly studied in this paper. The results show that the microstructure of the alloy is significantly changed by the squeeze casting process, and the mechanical properties of the alloy are improved remarkably.After being modified by Sr, the eutectic Si phase in the squeeze cast Al-17.5 Si alloy is changed into the tiny fibrous microstructure, and compared with the conventional sand casting, the tensile strength and elongation of the squeeze cast Al-17.5 Si alloy are improved 59% and 328.7%, respectively. However, with the addition of P in the squeeze cast Al-17.5 Si alloy, large amounts of coarse primary Si phase particles emerges in the microstructure of the alloy, and then the tensile strength and elongation of the alloy decrease obviously. So it is concluded that the best modification agent for the squeeze casting hypereutectic Al-Si alloy is Sr rather than P addition.
The effects of Sr and P modification on the microstructure and mechanical properties of the Al-17.5 Si alloy were mainly studied in this paper. The results show that the microstructure of the alloy is significantly changed by the squeeze casting process, and the mechanical properties of the alloy are improved remarkably.After being modified by Sr, the eutectic Si phase in the squeeze cast Al-17.5 Si alloy is changed into the tiny fibrous microstructure, and compared with the conventional sand casting, the tensile strength and elongation of the squeeze cast Al-17.5 Si alloy are improved 59% and 328.7%, respectively. However, with the addition of P in the squeeze cast Al-17.5 Si alloy, large amounts of coarse primary Si phase particles emerges in the microstructure of the alloy, and then the tensile strength and elongation of the alloy decrease obviously. So it is concluded that the best modification agent for the squeeze casting hypereutectic Al-Si alloy is Sr rather than P addition.
引文
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[15]Lu D H,Jiang Y H.Refinement of primary Si in hypereutectic Al-Si alloy by electromagnetic stirring[J].Journal of Materials Processing Technology,2007,189(6):13-18.
[2]Li R X,Liu L J,Zhang L J,et al.Effect of squeeze casting on microstructures and mechanical properties of hypereutectic Al-x Si alloys[J].Mater.Sci.Technol,2017,33:404-410.
[3]李润霞,刘兰吉,孙继鸿,等.挤压铸造对过共晶Al-Si-Cu-Mg合金组织与性能的影响[J].铸造,2017,66(4):367-371.
[4]Shi Y J,Liu L J,Zhang L,et al.Effect of squeeze casting process on microstructures and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy[J].Journal of Iron and Steel Research International,2017,24(9):957-965.
[5]Joseph S,Kumar S.Finite element analysis of stress evolution in Al-Si alloy[J].Journal of Materials Engineering and Performance,2015,24(1):253-260.
[6]Lados D A.Fatigue crack growth mechanisms in Al-Si-Mg alloys[J].Surface Engineering,2004,20(6):416-424.
[7]李润霞,张立军,刘兰吉,等.固溶处理对挤压铸造Al17.5Si4Cu0.5Mg0.1Mn合金显微组织及硬度的影响[J].铸造,2015,64(12):1226-1230.
[8]Lu D,Jiang Y,Guan G,et al.Refinement of primary Si in hypereutectic Al-Si alloy by electromagnetic stirring[J].Journal of Materials Processing Technology,2007,189(1-3):13-18.
[9]马广辉,李润霞,白彦华,等.低温下ZL101合金的裂纹扩展行为[J].铸造,2015,64(10):960-963.
[10]Haque M M,Syahriah N I,Ismail A.F.Effect of silicon on strength and fracture surfaces of aluminium-silicon casting and heat treated alloys[J].Key Engineering Materials,2006,306-308:893-898.
[11]Yeh J W,Liu W P.The cracking mechanism of silicon particles in an A357 aluminum alloy[J].Metallurgical and Materials Transactions A,1996,27(11):3558-3568.
[12]Lua L,Nogitab K,Dahlec A K.Combining Sr and Na additions in hypoeutectic Al-Si foundry alloys[J].Materials Science and Engineering A,2005,399(1-2):244-253.
[13]梁国萍,苏勇,刘福东,等.P+RE变质对过共晶Al-Si合金组织的影响[J].特种铸造及有色合金,2010,30(3):273-275.
[14]Zhang H H,Duan H L.Microstructure and mechanical properties of hypereutectic Al-Si alloy modified with Cu-P[J].Rare Metals,2008,27(10):59-64.
[15]Lu D H,Jiang Y H.Refinement of primary Si in hypereutectic Al-Si alloy by electromagnetic stirring[J].Journal of Materials Processing Technology,2007,189(6):13-18.