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.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
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 )
