Ab initio-based diffusion theory and tracer diffusion in Ni-Cr and Ni-Fe alloys
Ab initio-based diffusion theory and tracer diffusion in Ni-Cr and Ni-Fe alloys
复制标题
DOI：
10.1016/j.jnucmat.2010.08.003
复制
发表时间：
2010-10-30
影响因子：
3.1
通讯作者：
Morgan, D.
中科院分区：
文献类型：
--
作者：
Tucker, J. D.;Najafabadi, R.;Morgan, D.
本文采用从头算模型预测稀Ni-Cr和Ni-Fe合金的扩散相关热力学和动力学信息，然后利用建模结果确定空位和间隙介导扩散的现象学系数矩阵和示踪扩散系数。除了预测扩散系数外，这种基于从头算的方法还提供了通常无法通过实验获得的信息，包括对扩散的不同贡献结果表明：(1)Cr是Ni中通过空位扩散和间隙扩散扩散最快的物质，其次是Fe，最后是Ni。Cr扩散率的增强主要是由于迁移势垒和结合能的差异，而不是指前因子Ni中的Cr溶质与空位的相互作用较弱，但与间隙缺陷的结合较强(3)Cr在空位和间隙介导扩散中均表现出非arrhenius行为(4)在某些情况下，温度依赖的电子贡献对扩散有显著影响(5)Ni-Cr中的空位扩散机制随温度的变化而变化，导致空位-溶质阻力低于460 K (C) 2010 Elsevier B V All rights reserved
In this paper ab mum modeling is used to predict diffusion relevant thermodynamic and kinetic information for dilute Ni-Cr and Ni-Fe alloys The modeling results are then used to determine the phenomenological coefficient matrices and the tracer diffusion coefficients for both vacancy and interstitial mediated diffusion In addition to predicting diffusion coefficients this ab initio-based approach provides information typically inaccessible to experiments including the different contributions to diffusion (e g electronic excitation effects) the species dependence of interstitial diffusion and the deviations from Arrhenius-type relations which are often used to describe and extrapolate experimental diffusion data It is found that (1) Cr is the fastest diffusing species in Ni by both vacancy and interstitial diffusion followed by Fe and then Ni The enhanced diffusivity of Cr is primarily due to differences in migration barriers and binding energies not pre exponential factors (2) Fe and Cr solutes in Ni have weak interactions with vacancies but Cr solutes bind strongly to interstitial defects (3) Cr exhibits non-Arrhenius behavior in both vacancy and interstitial mediated diffusion (4) Temperature dependent electronic contributions have a significant impact on the diffusion in some cases (5) The vacancy diffusion mechanism in Ni-Cr changes as a function of temperature resulting in vacancy-solute drag below 460 K (C) 2010 Elsevier B V All rights reserved