无容器条件下Cu-Pb偏晶的快速生长

在落管无容器条件下实现了Cu-10%Pb亚偏晶和Cu_374%Pb偏晶的快速生长. 发现随着液滴 过冷度的增大, 亚偏晶中初生(Cu)相的生长形态经历“粗大枝晶→碎断枝晶→等轴晶”的转 变. 偏晶的组织形态从多个偏晶胞组织演化为单个偏晶胞组织. 理论计算表明，直径在1000 —60 μm之间的亚偏晶和偏晶合金液滴, 最大过冷度分别为269 K (02 TL_L )和245 K (02 TM_M). 亚偏晶合金中初生(Cu)枝晶的最大生长速度为24 m/s , 关键词： 无容器处理 深过冷 晶体生长 相分离

Rapid growth of Cu-Pb monotectics under containerless condition

Rapid growth of Cu_10%Pb hypermonotectics and Cu_374%Pb monotectics ha ve been achieved under containerless condition in drop tube. With the increase o f droplet undercooling, the primary(Cu) phase in hypermonotectios shows a morpho logy transition of “coarse dendrite→fragmental dentrite→equiaxed dentrite”. The momotectic microstructure transfers from multiple monotectic cell to single monotectic cell. Corresponding to the droplet diameter changing from 1000 to 100 μm, the calculated maximum undercooling for hypermonotectics and monotectics a re 269 K(02 TL_L) and 245 K (02 TM_M) respectively. The maximum grow th velocity of (Cu) dendrite is 24 m/s in Cu_10%Pb hypermonotectics. The growt h of primary (Cu) phase is always controlled by solute diffusion. The effect of Marangoni migration is more significant than that of Stokes motion, and the Mara ngoni migration velocity decreases when droplet diameter becomes small.