多元稀土对半固态A356铝合金梯度细化的研究
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摘要
基于稀土在铝合金中诱发共晶反应进而细化凝固组织的机制,设计了Gd-Nd-Y-Ce四元稀土复合细化剂,并辅以梯度保温措施,使半固态A356铝合金在保温阶段按照Al-RE共晶温度由高到低依次发生共晶反应,提高共晶产物的保存率,进而研究多元稀土对半固态A356铝合金凝固组织的梯度细化效果。结果表明:四元稀土按照正交试验设计的百分比添加量加入,在650℃浇注,并按照645℃/30 s-635℃/40 s-625℃/50 s-615℃/60 s进行梯度保温,615℃水淬脱模后,借助公式获得不同试样的细化特征参量。采用综合平衡法,对正交试验获得的极差R和试验指标K_i进行参数分析,获得四元稀土在优化方案下的最佳配比为:0.5%Gd+0.2%Nd+0.4%Y+0.2%Ce,试验验证此时A356铝合金初生相的平均等积圆直径为83.013μm,形状因子为0.817,细化效果最好。
Based on the mechanism of refining solidification structure resulted from eutectic reaction induced by rare earth in aluminum alloy, the Gd-Nd-Y-Ce quaternary rare earth composite refiner was designed,supplemented by gradient thermal insulation measures. Through making the semisolid A356 aluminum alloy in heat preservation phase in accordance with the Al-RE eutectic temperature from high to low successive eutectic reaction, to improve the survival of eutectic products was ensured. The effect of complex rare earth on semisolid A356 aluminum alloy solidification gradient refining was researched. The results show that the addition contents of quaternary rare earth were determined according to the orthogonal experiment design. Under the conditions of650 ℃ pouring temperature, and gradient thermal insulation according to the 645 ℃/30 s-635 ℃/40 s-625 ℃/50 s-615 ℃/60 s, and 615℃ water quenching demould, the refining characteristic parameters of different samples were obtained through the formula. By comprehensive balance method, analysis of the extremedifference R and test-index Ki of the orthogonal experiment parameters, the optimal proportion of the quaternary rare earth was found as follows: 0.5%Gd+0.2%Nd+0.4%Y+0.2%Ce. The primary phase A356 aluminum alloy of average equal-area diameter is 83.013 μm, and the shape factor is 0.817, the refining effect is best.
Based on the mechanism of refining solidification structure resulted from eutectic reaction induced by rare earth in aluminum alloy, the Gd-Nd-Y-Ce quaternary rare earth composite refiner was designed,supplemented by gradient thermal insulation measures. Through making the semisolid A356 aluminum alloy in heat preservation phase in accordance with the Al-RE eutectic temperature from high to low successive eutectic reaction, to improve the survival of eutectic products was ensured. The effect of complex rare earth on semisolid A356 aluminum alloy solidification gradient refining was researched. The results show that the addition contents of quaternary rare earth were determined according to the orthogonal experiment design. Under the conditions of650 ℃ pouring temperature, and gradient thermal insulation according to the 645 ℃/30 s-635 ℃/40 s-625 ℃/50 s-615 ℃/60 s, and 615℃ water quenching demould, the refining characteristic parameters of different samples were obtained through the formula. By comprehensive balance method, analysis of the extremedifference R and test-index Ki of the orthogonal experiment parameters, the optimal proportion of the quaternary rare earth was found as follows: 0.5%Gd+0.2%Nd+0.4%Y+0.2%Ce. The primary phase A356 aluminum alloy of average equal-area diameter is 83.013 μm, and the shape factor is 0.817, the refining effect is best.
引文
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[24]Yi R X,Xie S K,Zheng X Q,et al.Effect of RE on performance of semi-solid Al Si7 alloy[J].Key Engineering Materials,2010,43(9):581-584.
[25]姚丽娟,坚增运,朱满,等.富铈混合稀土对A356铝合金凝固组织和力学性能的影响[J].铸造,2016,65(2):166-171.
[26]刘政,谌庆春,许鹤君,等.多元稀土细化半固态A356铝合金初生α相的研究[J].轻金属,2015(1):49-53.
[27]毛卫民,白月龙,高松福,等.半固态Al Si7Mg铝合金的新型流变成形[J].材料研究学报,2006,20(5):469-473.
[28]蔡厚道.稀土元素Nd变质对ZL101铝合金的显微组织与力学性能的影响[J].铸造,2015,64(6):499-503.
[29]刘政,谌庆春.Gd对A356合金初生α相的细化机制[J].特种铸造及有色合金,2013,33(9):793-796.
[30]刘政,谌庆春,郭颂.铝钇共晶反应及其产物对亚共晶铝硅合金初生相的细化研究[J].稀有金属,2013,37(5):709-714.
[31]刘楚明,蒋树农,陈志勇.铝合金相图集[M].湖南:中南大学出版社,2014.
[2]陈志平,刘政,陈涛.电磁搅拌下半固态铝合金中磁感应强度的优化[J].铸造,2017,66(7):702-706.
[3]仲召军,李龙,周德敬.铸造Al-Si合金细化变化处理技术的研究进展[J].铸造,2016,65(3):242-247.
[4]Nogita K,Mc Donald S D,Dahle A K.Eutectic modification of Al-Si alloys with rare earth metals[J].Mater.Trans,2004,45:323-326.
[5]姚书芳,毛卫民,赵爱民.铸造铝合金细化变质处理的研究进展[J].铸造,2000,49(9):512-515.
[6]Jiang W,Fan Z,Dai Y,et al.Effects of rare earth elements addition on microstructures,tensile properties and fractography of A357 alloy[J].Materials Science&Engineering A,2014,597:237-244.
[7]刘政,胡咏梅.稀土细化剂对ZL101半固态组织影响的研究[J].铸造,2008,57(6):596-599.
[8]卢雅琳,于小健,李兴成,等.稀土Y对A356铝合金微观组织和性能的影响[J].铸造技术,2015,36(10):2415-2418.
[9]刘政,谌庆春.Ce对半固态A356铝合金初生α相细化机制的新探[J].铸造,2013,62(8):761-764.
[10]刘小梅,刘政,白光珠,等.Al-Sc共晶反应对半固态A356合金初生α相的影响[J].材料热处理学报,2016,37(7):130-135.
[11]唐小龙,彭继华,黄芳亮,等.混合稀土含量对A356铝合金组织结构的影响[J].中国有色金属学报,2010,20(11):2113-2116.
[12]Bita Pourbahari,Masoud Emamy,Mehrab Lotfpour,et al.Effects of La addition and heat treatment on the microstructure and tensile properties of A357 aluminum alloy[C]//Proceeding of 2015 International Conference on Chemical,Metallurgy and Environmental Engineering,2015,296-303.
[13]Hu Zhi,Yan Hong,Rao Yuan-sheng.Effects of samarium addition on microstructure and mechanical properties of as-cast Al-Si-Cu alloy[J].Transactions of Nonferrous Metals Society of China,2013,23(11):3228-3234.
[14]Liu Wenyi,Xiao Wenlong,Xu Cong,et al.Synergistic effects of Gd and Zr on grain refinement and eutectic Si modification of Al-Si cast alloy[J].Materials Science&Engineering A,2017,693:93-100.
[15]Pourbahari B,Emamy M.Effects of La intermetallics on the structure and tensile properties of thin section gravity die-cast A357Al alloy[J].Mater.Des,2016,94:111-120.
[16]Li J H,Wang X D,Ludwig T H,et al.Modification of eutectic Si in Al-Si alloys with Eu addition[J].Acta Mater,2015,84:153-163.
[17]Shi Z M,Wang Q,Zhao G,et al.Effects of erbium modification on the microstructure and mechanical properties of A356 aluminum alloys[J].Mater.Sci.Eng.A,2015,626:102-107.
[18]Shi Z M,Wang Q,Shi Y T,et al.Microstructure and mechanical properties of Gd modified A356 aluminum alloys[J].Rare Earths,2015,33(9):1004-1009.
[19]Prukkanon W,Srisukhumbowornchai N,Limmaneevichitr C.Influence of Sc modification on the fluidity of an A356 aluminum alloy[J].Alloy.Compd,2009,487(1-2):453-457.
[20]Xu C,Xiao W L,Zheng R X.The synergic effects of Sc and Zr on the microstructure and mechanical properties of Al-Si-Mg alloy[J].Mater.Des.2015,88:485-492.
[21]Prabhkiran Kaur,Dwivedi D K,Pathak P M.Effects of electromagnetic stirring and rare earth compounds on the microstructure and mechanical properties of hypereutectic Al-Si alloys[J].International Journal of Advanced Manufacturing Technology,2012,63(1-4):415-420.
[22]Yi H K,Zhang D,Sakata T,et al.Microstructures and La-rich compounds in a Cu-containing hypereutectic Al-Si alloy[J].Journal of Alloys and Compounds,2003,354(1-2):159-164.
[23]米国发,刘彦磊,文涛.稀土La+Sr复合变质对ZL101A合金组织的影响[J].铸造,2006,57(11):1142-1146.
[24]Yi R X,Xie S K,Zheng X Q,et al.Effect of RE on performance of semi-solid Al Si7 alloy[J].Key Engineering Materials,2010,43(9):581-584.
[25]姚丽娟,坚增运,朱满,等.富铈混合稀土对A356铝合金凝固组织和力学性能的影响[J].铸造,2016,65(2):166-171.
[26]刘政,谌庆春,许鹤君,等.多元稀土细化半固态A356铝合金初生α相的研究[J].轻金属,2015(1):49-53.
[27]毛卫民,白月龙,高松福,等.半固态Al Si7Mg铝合金的新型流变成形[J].材料研究学报,2006,20(5):469-473.
[28]蔡厚道.稀土元素Nd变质对ZL101铝合金的显微组织与力学性能的影响[J].铸造,2015,64(6):499-503.
[29]刘政,谌庆春.Gd对A356合金初生α相的细化机制[J].特种铸造及有色合金,2013,33(9):793-796.
[30]刘政,谌庆春,郭颂.铝钇共晶反应及其产物对亚共晶铝硅合金初生相的细化研究[J].稀有金属,2013,37(5):709-714.
[31]刘楚明,蒋树农,陈志勇.铝合金相图集[M].湖南:中南大学出版社,2014.