冷却速率和Er-Zr含量对Al-7Si-0.3Mg合金共晶组织的变质作用
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摘要
采用复合添加Er、Zr元素变质处理了Al-7Si-0.3Mg合金,通过控制冷却速率和Er、Zr元素添加量来变质合金中粗大的针片状共晶硅相。采用金相观察、扫描电镜、透射电镜、X-射线衍射及能谱分析等测试分析手段研究了Er、Zr元素对Al-7Si-0.3Mg合金中共晶硅相的变质作用,并探讨了Er、Zr复合变质机理。结果表明,当添加0.15wt%Er和0.15wt%Zr时,合金中的共晶硅相得到明显细化,不同的冷却速率也能显著改变共晶硅相形貌。当冷却速率为250～300℃/s并添加0.25wt%Er和0.25wt%Zr时,合金中共晶硅相变质为细小的纤维状。
The Al-7Si-0.3Mg alloy was modified by composite addition of Er and Zr elements. The coarse needle-like eutectic silicon phase in the alloy was modified by controlling the cooling rate and adding amount of Er and Zr elements. The modification of eutectic silicon phase in Al-7Si-0.3Mg alloy was studied by means of metallographic observation, scanning electron microscope, transmission electron microscope, X-ray diffraction and energy dispersive analysis. The compound modification mechanism of Er and Zr was also discussed. The results show that when 0.15 wt%Er and 0.15 wt%Zr are added,the eutectic silicon phase in the alloy is obviously refined, and the morphology of eutectic silicon phase is also changed at different cooling rates. When the cooling rate is 250-300℃/s and 0.25 wt%Er and 0.25 wt%Zr are added, the eutectic silicon phase of the alloy is modified to fine fibrous.
The Al-7Si-0.3Mg alloy was modified by composite addition of Er and Zr elements. The coarse needle-like eutectic silicon phase in the alloy was modified by controlling the cooling rate and adding amount of Er and Zr elements. The modification of eutectic silicon phase in Al-7Si-0.3Mg alloy was studied by means of metallographic observation, scanning electron microscope, transmission electron microscope, X-ray diffraction and energy dispersive analysis. The compound modification mechanism of Er and Zr was also discussed. The results show that when 0.15 wt%Er and 0.15 wt%Zr are added,the eutectic silicon phase in the alloy is obviously refined, and the morphology of eutectic silicon phase is also changed at different cooling rates. When the cooling rate is 250-300℃/s and 0.25 wt%Er and 0.25 wt%Zr are added, the eutectic silicon phase of the alloy is modified to fine fibrous.
引文
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[2]熊艳才,刘伯操.铸造铝合金现状及未来发展[J].特种铸造及有色合金,1998(4):1-5.
[3]Zhao H.Application of aluminum for the automotive industry[J].AutomotiveTechnologyandMaterials,1997(1):19-24.
[4]高士学,孙跃军,高艳静.稀土La对A356铝合金组织及硬度的影响[J].热加工工艺,2016,45(5):81-83.
[5]仲志国,王爱华,孙海斌,等.B,RE,La对锶变质A356铝合金微观组织及力学性能影响[J].热加工工艺,2010,39(1):6-9.
[6]Chou C Y.Lee S L.Lin J C.Effects and deformation characteristics of cross-channel extrusion process on pure Sn and Al-7Si-0.3Mgalloy[J].MaterialsChemistryand Physics,2008,107:193-199.
[7]Mulazimoglu M H,Tenekedjiev N,Closset B M.et al.Studies on the minor reactions and phases in strontium-treated aluminium-silicon casting alloys[J].Cast Metals,1993,6:16-28.
[8]LuShuzu,HellawellA.Themechanismofsilicon modification in aluminum-silicon alloys:impurity induced twinning[J].MetallurgicalTransactionsA1987,18(10):1721-1733.
[9]Kazuhiro Nogita,John Drennan,Arne Kristian Dahle.Evaluation of silicon twinning in hypo-eutectic Al-Si alloys[J].Materials Transaction,2003,44:625-628.
[10]Geng Huiyuan,Li Yanxiang,Chen Xiang,et al.Effects of boron on eutectic solidification in hypoeutectic Al-Si alloys[J].Scripta Materialia,2005,53:69-73.
[11]Marzouk M,Jain M,Shankar S.Effect of Sr-modification on the bendability of cast aluminum alloy A356 using digital image correlationmethod[J].MaterialsScience&EngineeringA,2014,598:277-287.
[12]Fatahalla N M,Hafiz M Abdulkhalek.Effect of microstructure on the mechanical properties and fracture of commercial hypoeutectic Al-Si alloy modified with Na,Sb and Sr[J].Journal of Materials Science,1999,34(14):3555-3564.
[13]Man Zhou,Jian Zengyun,Yao Lijuan,et al.Effect of mischmetal modification treatment on the microstructure,tensile properties,and fracture behavior of Al-7%Si-0.3%Mg foundry aluminum alloys[J].Journalof MaterialsScience,2011,46:2685-2694.
[14]季小兰,邢泽丙,聂祚仁.铒对Al-4.5Mg-0.7Mn合金组织与性能的影响[J].稀有金属,2006,33(4):462-465.
[15]杨军军,聂祚仁,金头男,等.稀土铒在Al-Zn-Mg合金中的存在形式与细化机理[J].中国有色金属学报,2004,14(4):620-626.
[16]杨军军,徐国富,聂祚仁,等.微量Er对高强铝合金组织与性能的影响[J].特种铸造及有色合金,2006,26(7):393-396.