Effect of sample diameter on primary dendrite spacing of directionally solidified Al-4%Cu alloy  

作　　者：屈敏 刘林 唐峰涛 张军 傅恒志 

机构地区：[1]State Key Laboratory of Solidification Processing, Northwestern Polytechnical University

出　　处：《中国有色金属学会会刊：英文版》2009年第1期1-8,共8页Transactions of Nonferrous Metals Society of China

基　　金：Project(50771081) supported by the National Natural Science Foundation of China

摘　　要：The relationship between primary dendrite arm spacing and sample diameter was studied during directional solidification for Al-4%Cu (mass fraction) alloy. It is shown that primary dendrite spacing is decreased with the decrease of the sample diameter at given growth rate. By regressing the relationship between primary dendrite arm spacing and the growth rate, the primary dendrite arm spacing complies with 461.76v-0.53, 417.92v-0.28 and 415.83v-0.25 for the sample diameter of 1.8, 3.5 and 7.2 mm, respectively. The primary dendrite spacing, growth rate and thermal gradient for different sample diameters comply with 28.77v-0.35G-0.70, 23.17v-0.35G-0.70 and 23.84v-0.35G-0.70, respectively. They are all consistent with the theoretical model λ1 =k b v-a1G-b1, and b1/a1=2. By analyzing the experimental results with classical models, it is shown that KURZ-FISHER model fits for the primary dendrite spacing in smaller sample diameters with weaker thermosolute convection. Whereas TRIVEDI model is suitable for describing primary dendrite arm spacing with a larger diameter (d>2 mm) where convection should be considered.The relationship between primary dendrite arm spacing and sample diameter was studied during directional solidification for Al-4%Cu （mass fraction） alloy. It is shown that primary dendrite spacing is decreased with the decrease of the sample diameter at given growth rate. By regressing the relationship between primary dendrite arm spacing and the growth rate, the primary dendrite arm spacing complies with 461.76v-0.53, 417.92v-0.28 and 415.83v-0.25 for the sample diameter of 1.8, 3.5 and 7.2 mm, respectively. The primary dendrite spacing, growth rate and thermal gradient for different sample diameters comply with 28.77v -0.35G-0.70, 23.17v-0.35G-0.70 and 23.84v-0.35G-0.70, respectively. They are all consistent with the theoretical model λ1 =kbv-a-a1G-b1, and b1/a1=2. By analyzing the experimental results with classical models, it is shown that KURZ-FISHER model fits for the primary dendrite spacing in smaller sample diameters with weaker thermosolute convection. Whereas TRIVEDI model is suitable for describing primary dendrite arm spacing with a larger diameter （d〉2 mm） where convection should be considered.

关 键 词：AL-CU合金 定向凝固 间距调整机制 实验 

分 类 号：TG146.21[一般工业技术—材料科学与工程]