钢中晶界区稀土稀土元素与杂质交互作用的电子理论研究

Theoretical Study of the Interaction between Rare Earth Elements and Impurities at Grain Boundaries in Steel

利用位错模型构造纯净的和稀土及杂质偏聚的晶界模型 ,用Recursion方法研究了稀土与杂质的交互作用对Fe 5 .3°小角度晶界的结合性质的影响。环境敏感镶嵌能和键级积分 (BOI)的计算结果表明 :钢中同时存在稀土和杂质时 ,稀土首先偏聚于晶界。稀土偏聚于晶界时 ,起到加强晶界的作用 ;杂质偏聚于晶界时却起到脆化的作用。钢中加入适量的稀土 ,既净化晶界 ,又提高钢的强度。这一结果从电子层次解释了稀土在钢中的作用机制 。

The model of dislocations was used to construct the atomic structure for the clean and rare earth elements and impurities doped grain boundary(GB). The influence of the interaction between rare earth elements and impurities on the cohesive properties of Fe 5.3° low angle GB were investigated by the Recursion method. The calculated results of ESE show that the preferential segregation of rare earth elements towards GBs exists. Calculations of bond order integrals(BOIs) show that rare earth elements increase the cohesive strength of low angle GB, and impurities such as S, P weaken the intergranular cohesion of the GB. So proper quantity rare earth elements added in steel not only clean the GBs off other harmful impurities, but also enhance the intergranular cohesion. This elucidates the mechanism of effect of rare earth elements in steel at electronic level and offers theoretical guidance for applications of rare earth elements in steels.