A simple yet general model of binary diffusion coefficients emerged from a comprehensive assessment of 18 binary systems
A simple yet general model of binary diffusion coefficients emerged from a comprehensive assessment of 18 binary systems
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DOI：
10.1016/j.actamat.2021.117077
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发表时间：
2021-08
期刊：
影响因子：
9.4
通讯作者：
W. Zhong;Qiaofu Zhang;Ji-Cheng Zhao
中科院分区：
文献类型：
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作者：
W. Zhong;Qiaofu Zhang;Ji-Cheng Zhao
这项研究是迄今为止最全面的测试，旨在确定最佳数量的拟合参数的一个可靠的数学描述的二元固溶体的扩散行为。我们对18个不同的二元体系进行了系统的测试，得到了一个令人惊讶的简单模型，只有一个拟合参数/常数，可以从实验扩散数据中进行评估。模型中的其余量是纯元素的自扩散系数和杂质（稀）扩散系数以及热力学因子，这些热力学因子可以通过对相关二元体系的CALPHAD热力学评估来计算。单参数Z-Z-Z模型已被证明是非常可靠和稳健的，因为在本研究中测试的18个二元系统包括非常不对称的系统，如Co-Pd和Fe-Pd以及Nb-Ti，其实验扩散系数数据覆盖约9个数量级，温度范围跨越约1200°C（从约800°C到约2000°C）。Z-Z-Z模型允许在从相互扩散或所有实验扩散数据评估唯一常数之后，可靠地计算任何温度下任何组合物的示踪剂和本征扩散系数。这样一个简单而强大的模型从二元到三元和更高阶系统的扩展将导致拟合参数的大幅减少和未来多组分扩散（原子迁移率）数据库的可靠性的增强，用于模拟材料中的动力学过程。
This study is the most comprehensive test to date aiming at defining the optimal number of fitting parameters for a reliable mathematical description of the diffusion behavior of a binary solid solution. Our systematic test of 18 diverse binary systems has yielded a surprisingly simple model with only one fitting parameter/constant which can be evaluated from experimental diffusion data. The rest of the quantities in the model are the self-diffusion and impurity (dilute) diffusion coefficients of thepure elementsand the thermodynamic factor which can be computed from a CALPHAD thermodynamic assessment of the pertinent binary system. The 1-parameter Z-Z-Z model has been demonstrated to be very reliable and robust since the 18 binary systems tested in this study include very asymmetrical systems such as Co-Pd and Fe-Pd as well as Nb-Ti whose experimental diffusion coefficient data cover ~9 orders of magnitude and over a temperature range spanning ~1200°C (from ~800°C to ~2000°C). The Z-Z-Z model allows both tracer and intrinsic diffusion coefficients to be reliably computed for any composition at any temperature after the sole constant is evaluated from the interdiffusion or all experimental diffusion data. Extension of such a simple and robust model from binary to ternary and higher order systems will lead to a substantial reduction of fitting parameters and an enhancement of the reliability of future multicomponent diffusion (atomic mobility) databases for simulation of kinetic processes in materials.