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1、3612002M1上 海 交 通 大 学 学 报JOURNAL OF SHANGHAI JIAOTONG UNIVERSITYVol. 36 No. 1Jan. 2002l: 2001-03-13:SEo973p$?Z?(G1999064900-4)Te:5(1972-),3,Z,pV3,VYE%hF.cI|:1006-2467(2002) 01-0051-048)%Al-SiF何树先,王俊,孙宝德,周尧和(ZYvS,Z200030)K1: 利用正交试验的方法对熔体温度处理细化亚共晶Al-Si合金的凝固组织进行了研究.结果表明,经过熔体温度处理后,凝固组织中一次枝晶尺寸明显减小,长的树枝晶变为
2、短的树枝晶或等轴晶,并且枝晶数量明显增多;二次枝晶臂间距变化不明显.从原子团簇的角度分析认为,这是由于高、低温熔体混合后,低温熔体中大的原子团簇得到细化,从而导致混合熔体中形核质点增殖的结果.研究同时发现,高、低温熔体的混合方式对熔体温度处理效果有直接影响,熔体的均匀混合有利于增大熔体凝固过冷度,减小临界晶核半径,促进凝固组织的细化.1oM: 亚共晶铝硅合金; 熔体温度处理; 凝固组织; 细化ms|: TG 111; TG 290DSM: ASolidification Structure of HypoeutecticAl-Si Alloy Refined by Melt Thermal T
3、reatmentHE Shu-xian,WANG Jun,SUN Bao-de,ZHOU Yao-he(School of Materials Science and Eng., Shanghai Jiaotong Univ., Shanghai 200030, China)Abstract: The solidification structure which is refined by the melt thermal treatment (MTT) process wasstudied with orthogonal experiment. The results show that t
4、he first dendrite size (FDS) reduces obvious-ly, and the long dendrites turn into short ones or equiaxed grains and the amount of the dendrites increas-es. However, thesecond dendritearm spacing (SDAS) changes little. This is resulted from the multiplica-tion of theoriginal nucleates or clusters in
5、the low temperaturemelt. And themixing mode of high and lowtemperature melts play an important rolein the MTT process. Themulti-hole modeis more beneficial thanthe mono-hole one to make the mixing melt homogeneously, to increase the melt solidifying undercooling,reducing the critical nucleate radius
6、, and so the solidification structure is refined best.Key words: hypoeutectic Al-Si alloy; melt thermal treatment; solidification structure; refinementh#hV%,V4/ah,4F?,p,4hqVFK?,h,Mvo2p,#q.+EM,%ZTvm,i4%#ZE.FE1=3E,-1_8F%4,Al-Ti-BW;1y%E2aZE3asVZE4#VE5 .8)%FX-SE20W60M4, 90MOhmi6j8T99BXVAl-SiV8)3Si%rT.3
7、RFDL, Cnull RFDL, A,iYLFDLKAy8,8600CHLFDLKl;Qa8ZT,d%Tz;78,5LFDLl.YV,1%lLFDLKDZA2B1C1,:8950C,8600C,ZTd%T.V2LTTab.2The results of orthogonal experimentk|ky0A B CNSSDAS/nullm LFDL/nullm1 1 1 122. 07 266. 02 1 2 2 23. 03 251. 83 1 3 3 21. 77 267. 84 2 1 3 23. 65 230. 65 2 2 1 21. 73 287. 66 2 3 2 23. 28
8、 241. 67 3 1 2 23. 55 235. 08 3 2 3 23. 60 203. 49 3 3 1 19. 25 322. 0RDAS122. 2923. 0921. 02RDAS2 22. 89 22. 79 23. 29RDAS3 22. 13 21. 43 23. 01RDAS 0. 76 1. 66 2. 27RFDL1 261. 87 243. 87 237. 00RFDL2 253. 27 247. 60 268. 13RFDL3 253. 47 277. 13 263. 47RFDL 8. 60 33. 26 31. 13Vm2(a)Vn,?/%F,BQ3nullE
9、s?r,jv;7V8)%F,jAhl,iO_%l?Z(nm2(b) ).m3Vn,d%TZT%F%rT11dTz,%kF1%.52上海交通大学学报36m2kMF(100)Fig. 2The optical microstructure of the samplem3ZT%kMF(100)Fig. 3The optical microstructure of the sampleobtained by different mixing mode2. 2s)2. 2.1高、低温熔体温度对组织细化的影响k?C,8)Y%FKAy08,%F%rTz.s,8,+Y)%AMLW8,iv%MMv0v%M,m4(a)U.t0v%MVT%H,V79F,%FT.86,8v0v4%Mh,8rMH,8CB(10 ,nm4(b).|BV8iv8y,VP8W$s,78$F,8-,848=|ivBVv8,nm4(c).8)%H18,88M?P8,7O?P910.9MMMAM0v,yN,89,%F%.2.2. 2高、低温熔体混合方式对组织细化的影响1ZTE)%FY,sE)+%,ZTYv.%F%B
