稀土熔剂对A356合金二次枝晶臂间距的影响  

Effect of rare earth flux on secondary dendrite arm spacing of A356 alloy

作　　者：倪红军[1] 孙宝德[1] 蒋海燕[1] 丁文江[1] 

机构地区：[1]上海交通大学材料科学与工程学院

出　　处：《中国有色金属学报》2002年第5期940-944,共5页The Chinese Journal of Nonferrous Metals

基　　金：国家重点基础研究发展规划资助项目 (G19990 6 490 0 )

摘　　要：将含有稀土的熔剂JDN -Ⅰ用于覆盖处理A35 6合金。实验结果表明 ,该稀土熔剂对A35 6合金的二次枝晶臂间距dDAS值有着较大的影响。无熔剂覆盖时 ,水淬获得的dDAS值比空冷下降 30 .8% ;有JDN -Ⅰ熔剂覆盖时 ,水淬获得的dDAS值比空冷下降 88.2 % ;水淬时 ,有熔剂覆盖的dDAS值比无熔剂覆盖低 77.7% ;空冷时 ,有熔剂覆盖的dDAS值比无熔剂覆盖高 2 3.3%。分析认为 ,存在 2个临界冷速v1和v2 :当冷速v <v1时 ,dDAS值由液相线斜率决定 ;当v >v2 时 ,dDAS值由JDN -Ⅰ熔剂中的稀土含量决定 ;当v1<v <v2 时 。A rare earth flux-JDN-Ⅰ was used for A356 alloys by covering on the surface of the melt. The experimental results indicate that the rare earth flux affects the secondary dendritic arm spacing (d DAS) of A356 alloy. The d DAS obtained by water-quenching decreases by 30.8% in comparison with that by air-cooling without the covering of the flux, while the d DAS obtained by water-quenching decreases by 88.2% in comparison with that by air cooling with the covering of JDN-Ⅰ flux. It is suggested that there are two critical cooling rates,v 1 and v 2. If the cooling rate v<v 1, the d DAS is primarily determined by slope of liquidus(M) which is determined by the compositions, diffusion coefficient of the alloy. If v>v 2, the d DAS is determined by the of JDN-Ⅰ flux and solidification time t f. If v 1<v<v 2, the d DAS is determined by t f , and M together.

关 键 词：稀土熔剂 A356合金 二次技晶臂间距 JDN—I 净化 铝合金熔体 力学性能 

分 类 号：TG146.21[一般工业技术—材料科学与工程]