SiC对Al-18Si合金中初生Si细化行为的研究
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摘要
采用一种富含SiC晶种的Al-30Si-5C晶种合金对Al-18Si合金进行细化试验。结果表明,该晶种合金对初生Si有良好的细化效果,添加量为1%、搅拌后保温15min,初生Si平均晶粒尺寸由108μm细化至35μm。由EDS及DSC分析可知,SiC晶种为初生Si的异质形核衬底。细化机理为:(1)基本满足要求的错配度;(2)Si在SiC表面吸附及偏聚使富Si层优先满足形核过冷度需求;(3)SiC台阶凹面形貌有利于晶胚形核。
The refining behavior and heterogeneous nucleating behavior of Al-30 Si-5 C master alloy on primary Si in Al-18 Si alloys were described.The results show that the mechanical stirring can accelerate the refining effect of Al-30 Si-5 Cmaster alloy on primary Si and a shorter holding time is also a promotion factor.The average size of primary Si grains can be decreased from 108μm to 35μm with 1% Al-SiC master alloy addition by applying mechanical stirring and holding temperature for 15 min.The EDS and DSC analysis indicates that SiC particles can act as the heterogeneous nucleation substrate of primary Si.Besides,the refining mechanism was discussed from the following aspects:(1)the basically appropriate crystallographic orientation relationship between Si phase and SiC phase,(2)adsorption and segregation of Si element on SiC particles enabled the rich Si layer to satisfy the nucleation supercooling degree,(3)surface morphology of SiC particles favorable for nucleation of embryos.
The refining behavior and heterogeneous nucleating behavior of Al-30 Si-5 C master alloy on primary Si in Al-18 Si alloys were described.The results show that the mechanical stirring can accelerate the refining effect of Al-30 Si-5 Cmaster alloy on primary Si and a shorter holding time is also a promotion factor.The average size of primary Si grains can be decreased from 108μm to 35μm with 1% Al-SiC master alloy addition by applying mechanical stirring and holding temperature for 15 min.The EDS and DSC analysis indicates that SiC particles can act as the heterogeneous nucleation substrate of primary Si.Besides,the refining mechanism was discussed from the following aspects:(1)the basically appropriate crystallographic orientation relationship between Si phase and SiC phase,(2)adsorption and segregation of Si element on SiC particles enabled the rich Si layer to satisfy the nucleation supercooling degree,(3)surface morphology of SiC particles favorable for nucleation of embryos.
引文
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[3]EIKEN J,APEL M,LIANG S M,et al.Impact of P and Sr on solidification sequence and morphology of hypoeutectic Al-Si alloys:Combined thermodynamic computation and phase-field simulation[J].Acta Materialia,2015,98:152-163.
[4]王娜,周志敏.近液相线半连续铸造过程中A390合金中初生硅的形成机理[J].中国有色金属学报,2010,20(10):1 895-1 899.
[5]SUN Y J,WANG Q L,GENG H R.Effects of complex modificating technique on microstructure and mechanical properties of hypereutectic Al-Si alloys[J].Journal of Materials Science,2012,47(5):2 104-2 109.
[6]刘相法,朱利民.Al-P晶种合金在Al-Si活塞合金中的应用[J].特种铸造及有色合金,2002(6):43-45.
[7]陈跃,邢建东.增强颗粒对铝基复合材料摩擦学性能的影响[J].摩擦学学报,2001,21(4):251-255.
[8]MA P,ZOU C M,WANG H W,et al.Effects of high pressure and SiC content on microstructure and precipitation kinetics of Al-20Si alloy[J].Journal of Alloys and Compounds,2014,586:639-644.
[9]隋贤栋,罗承萍.铸造SiCp/Al-Si复合材料中的“界面Si”行为[J].中国有色金属学报,1999,9(S1):20-24.
[10]张金山,许春香,韩富银.复合变质对过共晶高硅铝合金组织和性能的影响[J].中国有色金属学报,2002,12(S1):107-110.
[11]ZHANG M X,KELLY P M.Edge-to-edge matching and its applications[J].Acta Materialia,2005,53:1 073-1 085.
[12]YANG L,XIA M,LI J G.Epitaxial growth in heterogeneous nucleation of pure aluminum[J].Materials Letter,2014,132:52-54.
[13]GUI M C,KANG S B.Aluminum hybrid composite coatings containing SiC and graphite particles by plasma spraying[J].Materials Letters,2001,51(5):396-401.
[14]BRAMFITT B L.The effect of carbide and nitride additions on the heterogeneous nucleation behavior of liquid iron[J].Metallurgical Transactions,1970,B1(7):1 987-1 995.
[15]KIM J K,ROHATGI P K.Nucleation on ceramic particles in cast metal-matrix composites[J].Metallurgical and Materials Transactions,2000,A31(4):1 295-1 304.
[16]SMITH W F,HASHEMI J.Foundations of Materials Science and Engineering[M].New York:Mcgraw-Hill,2006.
[17]QIAN M.Heterogeneous nucleation on potent spherical substrates during solidification[J].Acta Materialia,2007,55(3):943-953.