Modelling the influence of grain-size-dependent solute drag on the kinetics of grain growth in nanocrystalline materials
Modelling the influence of grain-size-dependent solute drag on the kinetics of grain growth in nanocrystalline materials
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DOI：
10.1016/s1359-6454(99)00079-8
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发表时间：
1999-05
期刊：
影响因子：
9.4
通讯作者：
A. Michels;C. Krill;H. Ehrhardt;R. Birringer;D. T. Wu
中科院分区：
文献类型：
--
作者：
A. Michels;C. Krill;H. Ehrhardt;R. Birringer;D. T. Wu
在纳米材料中，当晶界迁移受溶质(杂质)阻力控制时，伴随着晶粒生长的总晶界面积的较大相对变化对晶界生长动力学具有潜在的强烈影响。随着晶界面积的减小，偏析到晶界的溶质或杂质原子的浓度有望迅速增加，从而引入晶粒度对晶界迁移的阻滞力。我们修正了Burke方程--它假定阻力与平均颗粒尺寸无关--以考虑晶界钉扎与颗粒尺寸的线性关系。由此得到的颗粒生长曲线的形式与Burke的解惊人地相似；事实上，不断地重新调整边界迁移率参数足以将一种解决方案近似映射到另一种解决方案上。因此，由迁移率参数的温度依赖关系计算出的晶界运动激活能对于两个模型来说是相同的。这一事实解释了为什么Burke解成功地拟合了在纳米晶体材料等体系中获得的颗粒生长数据，对于这些体系，与颗粒尺寸无关的溶质阻力的假设是不正确的。
The large relative change in total grain-boundary area that accompanies grain growth in a nanocrystalline material has a potentially strong influence on the kinetics of grain growth whenever grain-boundary migration is controlled by solute (impurity) drag. As the grain-boundary area decreases, the concentration of solute or impurity atoms segregated to the boundaries is expected to increase rapidly, introducing a grain-size dependence to the retarding force on boundary migration. We have modified the Burke equation—which assumes the drag force to be independent of the average grain size—to take into account a linear dependence of grain-boundary pinning on grain size. The form of the resulting grain-growth curve is surprisingly similar to Burke's solution; in fact, a constant rescaling of the boundary mobility parameter is sufficient to map one solution approximately onto the other. The activation energies for grain-boundary motion calculated from the temperature dependence of the mobility parameter are therefore identical for both models. This fact provides an explanation for the success of Burke's solution in fitting grain-growth data obtained in systems, such as nanocrystalline materials, for which the assumption of grain-size-independent solute drag is incorrect.