本文利用第一原理离散变分方法,计算了轻杂质P、N在体心Fe∑3[10](111)晶界和Fe(111)表面的偏聚能,从能量方面对P,N的韧脆机制进行了探讨.结果表明,P在晶界上的偏聚能比表面上更高,更有利于偏聚在表面而非晶界,而N则相反.因此,P为脆性杂质,N为韧性杂质,此结果与实验观察相符.还分析了造成这一结果的化学因素和力学因素的影响,指出了在计算中对原子结构进行弛豫的必要性.
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