Dislocation cross-slip in fcc solid solution alloys
Dislocation cross-slip in fcc solid solution alloys
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DOI：
10.1016/j.actamat.2017.02.027
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发表时间：
2017-04
期刊：
影响因子：
9.4
通讯作者：
W. Nöhring;W. Curtin
中科院分区：
文献类型：
--
作者：
W. Nöhring;W. Curtin
交叉滑移是螺位错运动的基本过程，在金属加工硬化和位错结构的演变中起着重要作用。交叉滑移已在纯 FCC 金属中得到广泛研究，但很少在 FCC 固溶体中进行研究。这里，使用原子方法计算了不同溶质浓度范围内 Ni-Al、Cu-Ni 和 Al-Mg 三种代表性体系的固溶体中的交叉滑移转变路径。使用真正的随机合金及其相应的平均合金对应物的研究允许独立评估（i）真正的随机合金随机性中空间溶质分布的波动和（ii）平均合金性能（例如堆垛层错能）的作用。结果表明，溶质波动主导了活化能垒，即平均活化能垒周围存在较大的样品间变化。激活势垒的变化与初始状态和最终状态之间的能量差线性相关。该能量差的分布可以根据溶质/位错相互作用能进行分析计算。因此，可以从无参数解析模型准确地确定交叉滑移活化能的分布。然后确定活化能的统计分布对实际合金中横向滑移速率的影响。
Cross-slip is a fundamental process of screw dislocation motion and plays an important role in the evolution of work hardening and dislocation structuring in metals. Cross-slip has been widely studied in pure FCC metals but rarely in FCC solid solutions. Here, the cross-slip transition path in solid solutions is calculated using atomistic methods for three representative systems of Ni-Al, Cu-Ni and Al-Mg over a range of solute concentrations. Studies using both true random alloys and their corresponding average-alloy counterparts allow for the independent assessment of the roles of (i) fluctuations in the spatial solute distribution in the true random alloy randomness and (ii) average alloy properties such as stacking fault energy. The results show that the solute fluctuations dominate the activation energy barrier, i.e. there are large sample-to-sample variations around the average activation barrier. The variations in activation barrier correlate linearly with the energy difference between the initial and final states. The distribution of this energy difference can be computed analytically in terms of the solute/dislocation interaction energies. Thus, the distribution of cross-slip activation energies can be accurately determined from a parameter-free analytic model. The implications of the statistical distribution of activation energies on the rate of cross-slip in real alloys are then identified.