熔体温度处理细化亚共晶Al-Si合金组织.pdfVIP

36 1 上 海 交 通 大 学 学 报 Vol. 36 No. 1 2002 1 JOURNAL OF SHANGHAI JIAOT ONG UNIVERSIT Y Jan. 2002 : 1006-2 67( 2002) 01-0051-0 - Al Si 何树先, 　王　俊, 　孙宝德, 　周尧和 ( , 200030) : 利用正交试验的方法对熔体温 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 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 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 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 , 减小临界晶核半径, 促进凝固组织的细化. : 亚共晶铝硅合金; 熔体温 处理; 凝固组织; 细化 : T G 111; T G 290: A Solidif icat ion St ruct ure of Hypoeutect ic Al-Si Alloy Ref ined by Melt Thermal Treat ment - , , - , - H E Sh u x ian WA N G J un S UN B ao de ZH OU Yao he ( School of M aterials Science and Eng . , Shanghai Jiaotong Univ. , Shanghai 200030, China) : ( ) Abstract The solidification structure w hich is refined by the melt thermal treatment MT T process w as studied with orthogonal experiment. The results show that the 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 How ever the second dendrite arm spacing SDAS changes little This is resulted from the multiplica- tion of the original nucleates or clusters in the low temperature melt And the mixing mode of high and low. temperature melts play an important role in the MT T process. The multi-hole mode is more beneficial than the mono-hole one to make the mixing melt homogeneously , to increase the m