Effects of dilute substitutional solutes on interstitial carbon in α-Fe: Interactions and associated carbon diffusion from first-principles calculations
Effects of dilute substitutional solutes on interstitial carbon in α-Fe: Interactions and associated carbon diffusion from first-principles calculations
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DOI：
10.1103/physrevb.90.024103
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发表时间：
2014-07
影响因子：
3.7
通讯作者：
Peitao Liu;Weiwei Xing;Xiyue Cheng;Dianzhong Li;Yiyi Li;Xing-Qiu Chen
中科院分区：
文献类型：
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作者：
Peitao Liu;Weiwei Xing;Xiyue Cheng;Dianzhong Li;Yiyi Li;Xing-Qiu Chen
通过第一性原理计算结合动力学蒙特卡罗模拟，我们系统地研究了稀替代溶质对碳在α - Fe中行为的影响。我们的结果揭示了以下几点：（i）在没有铁空位的情况下，由于应变消除，大多数溶质与碳之间的相互作用是排斥的，而锰由于局部铁磁耦合效应与其最近邻的碳有微弱的吸引作用。（ii）铁空位的存在导致所有溶质与碳之间产生吸引作用。特别是，锰 - 空位对与碳表现出异常大的结合能，为 - 0.81 eV。（iii）合金添加显著影响铁基体中碳的原子尺度浓度分布和化学势。其中，锰和铬提高碳的化学势，而铝和硅降低它。（iv）在合金溶液的稀浓度范围内，溶质浓度和温度相关的碳扩散率表明，锰对碳扩散影响较小，而铬（铝或硅）显著阻碍碳扩散。我们的结果对更好地理解与铁素体钢中碳溶解度极限、碳微观偏析和碳化物沉淀相关的实验观察具有一定的启示意义。
By means of first-principles calculations coupled with the kinetic Monte Carlo simulations, we have systematically investigated the effects of dilute substitutional solutes on the behaviors of carbon in $\ensuremath{\alpha}$-Fe. Our results uncover the following. (i) Without the Fe vacancy the interactions between most solutes and carbon are repulsive due to the strain relief, whereas Mn has a weak attractive interaction with its nearest-neighbor carbon due to the local ferromagnetic coupling effect. (ii) The presence of the Fe vacancy results in attractive interactions of all the solutes with carbon. In particular, the Mn-vacancy pair shows an exceptionally large binding energy of $\ensuremath{-}$0.81 eV with carbon. (iii) The alloying addition significantly impacts the atomic-scale concentration distributions and chemical potential of carbon in the Fe matrix. Among them, Mn and Cr increase the carbon chemical potential, whereas Al and Si reduce it. (iv) Within the dilute scale of the alloying solution, the solute concentration- and temperature-dependent carbon diffusivities demonstrate that Mn has a little impact on the carbon diffusion, whereas Cr (Al or Si) remarkably retards the carbon diffusion. Our results provide a certain implication for better understanding the experimental observations related with the carbon solubility limit, carbon microsegregation, and carbide precipitations in the ferritic steels.