RE_2O_3对钢液凝固时异质形核促进效用的晶体学计算

Crystallographic Calculation about Heterogeneous Nucleation Potency of RE_2O_3 in Liquid Steel

针对钢中添加稀土镧、铈形成的高熔点夹杂物相Ce_2O_3和La_2O_3,利用边-边匹配模型计算其与初生相(δ-Fe或γ-Fe)之间的原子匹配情况,从晶体学角度预测其作为钢液凝固时初生相异质形核核心的可能性及效用,并为理解稀土细化钢的凝固组织的作用机理提供新的见解。结果表明,Ce_2O_3和La_2O_3均可作为初生相δ-Fe及γ-Fe异质形核的核心;Ce_2O_3和La_2O_3均可有效细化δ-Fe晶粒,但其细化γ-Fe晶粒的效果远不如其细化δ-Fe晶粒的效果;对于γ-Fe,La_2O_3的细化效果较Ce_2O_3稍好。

Edge-to-Edge Matching Model was used to calculate the atomic matching between the RE inclusions, namely Ce_2O_3 and La_2O_3, and the primary phase（both δ-Fe and γ-Fe）, in order to predict the possibility and the potency of RE_2O_3 as the heterogeneous nucleation sites in liquid steel. The research also provides new insight into the understanding of the grain refinement mechanism of rare earth in the solidification of steels from the point of view of crystallography. The results show that both Ce_2O_3 and La_2O_3 are potential nucleant for heterogeneous nucleation of both δ-Fe and γ-Fe primary phases during solidification of steels. But, the grain refining effect of Ce_2O_3 and La_2O_3 for δ-Fe is better than that for γ-Fe. Moreover, for γ-Fe, the La_2O_3 is more efficient than Ce_2O_3.