溶质扩散控制层片共晶生长

LAMELLAR EUTECTIC GROWTH CONTROLLED BY SOLUTE DIFFUSION

基于平界面溶质扩散假设,改进界面物质守恒边界条件求得了层片共晶稳态生长的溶质边界层.结果表明,层片共晶组织生长过程中沿生长方向的溶质边界层与沿界面方向的溶质边界层相关.对CBr_4-C_2Cl_6透明合金系的分析表明,共晶合金层片组织生长过程中界面处液、固相平均成分的差值随凝固速率增大而增大.合金成分偏离共晶成分时,界面处液相平均成分与共晶成分非常接近.在给定的凝固速率下,共晶相界面处液、固相平均成分差值与层片宽度的比值随合金成分的不同而不同.

Based on the planar diffusion assumption, the solute boundary layer in lamellar eutectic growth under steady-state is estimated by means of modifying the conservation of mass at solid/liquid interface. It is found that the solute boundary layer along the growth direction is related to that along the solid/liquid interface. For transparent organic system CBr4-C2Cl6 with eutectic composition, the difference in average compositions of the solid and the liquid at solid/liquid interface increases with increasing in growth rate. The average composition in the liquid at solid/liquid interface still closes to the eutectic one as the initial composition of the alloy is apart from the eutectic point. In addition, for a fixed growth rate, the ratio of the difference in average composition to the lamellar width changed with initial composition of the alloy is noticeably distinct.