合金凝固过程中的溶质再分配与成分偏析

SOLUTE REDISTRIBUTION AND SEGREGATION IN SOLIDIFICATION PROCESS

在平衡凝固、近平衡凝固、非平衡凝固3个层次上讨论了凝固过程的溶质分配因数,综述了平界面凝固过程和枝晶凝固过程的溶质再分配规律,提出了宏观偏析的控制参数,并以合金钢为例,导出了该控制参数与合金成分的关系。

The researches on solute redistribution coefficients for equilibrium, near equilibrium and non-equilibrium solidification processes were first analyzed in this review paper. Then, different models since 1950s for the solute redistribution during directional solidification process with planar interface were summarized. The so-called second-order opposite diffusion compensation method (SODCM) presented by the author was described in details. Third, the solute distribution in dendritic solidification process and the resulted segregation were discussed. It is concluded that the problem could be described by (?)s-WL functions. Among different models, the one obtained by the present authors in 1994 was explained. The macro segregation is mainly caused by liquid flow in mush zone. A parameter about the driving force for the liquid flow in the mush zone deduced by the present author is also described. The parameter can be thought as the controlling parameter for the formation of macro segregation. The relationship between the parameter and the compositions in steel is also given in the paper.