Escola Politécnica/Departamento de Engenharia Metalúrgica e de Materiais, Universidade de São Paulo, Brazil.
J Phys Condens Matter. 2013 Jan 16;25(2):025401. doi: 10.1088/0953-8984/25/2/025401. Epub 2012 Nov 26.
Atomistic simulations with an EAM interatomic potential were used to evaluate carbon-dislocation binding energies in bcc iron. These binding energies were then used to calculate the occupation probability of interstitial sites in the vicinity of an edge and a screw dislocation. The saturation concentration due to carbon-carbon interactions was also estimated by atomistic simulations in the dislocation core and taken as an upper limit for carbon concentration in a Cottrell atmosphere. We obtained a maximum concentration of 10 ± 1 at.% C at T = 0 K within a radius of 1 nm from the dislocation lines. The spatial carbon distributions around the line defects revealed that the Cottrell atmosphere associated with an edge dislocation is denser than that around a screw dislocation, in contrast with the predictions of the classical model of Cochardt and colleagues. Moreover, the present Cottrell atmosphere model is in reasonable quantitative accord with the three-dimensional atom probe data available in the literature.
使用 EAM 原子间势的原子级模拟来评估体心立方铁中碳-位错结合能。然后，利用这些结合能来计算刃型和螺型位错附近间隙位置的占据概率。通过在位错核内的原子级模拟来估算由于碳-碳相互作用而导致的饱和浓度，并将其作为科恰特气氛中碳浓度的上限。我们在距位错线 1nm 半径范围内获得了 T=0K 时最大浓度为 10±1at.%C。在位错线周围的碳空间分布表明，与螺型位错相比，与刃型位错相关的科恰特气氛更密集，这与科恰特和同事的经典模型的预测相反。此外，目前的科恰特气氛模型与文献中可用的三维原子探针数据在定量上是合理一致的。
