一种新的滑动剪切技术测量Al-Cu合金的互扩散系数

A new sliding cell technique for diffusion coefficient measurements in liquid Al-Cu alloys

液态金属扩散系数是液态金属最重要物理参量之一,也是金属材料设计与工业生产应用的必要参数.本文建立了一种新的测量液态金属互扩散系数的技术——滑动剪切技术,该技术避免了传统长管测量技术中升温过程的影响,能够显著地提高测量互扩散系数的精度.利用该技术测量了1023 K时Al70Cu30-Al90Cu10扩散偶的扩散系数,发现扩散系数在所研究的成分范围内呈现出有规律的成分依赖趋势.该结果为理解扩散的微观机制和其结构依赖关系提供了新的证据.

The diffusion coefficient is one of the most important physical parameters in liquid metals, and also an essential parameter for the material design and industrial application. However, available experimental data of the diffusion coefficients are actually not sufficient due to the difficulties of the diffusion measurement. In this work, a new kind of diffusion measurement technique： the sliding cell technique is presented. By employing this technique, the influence of the heating process on the isothermal liquid diffusion procedure is avoided, so that the measurement accuracy is significantly enhanced compared to the conventional long capillary technique. Using the novel technique, the liquid diffusion coefficients of the diffusion couple Al70Cu30-Al90Cu10 at 1023 K were measured. It is found that the measured diffusion coefficients show a clear composition dependent tendency. Such a tendency is useful for the understanding of the mechanism of atomic diffusion and the correlation between diffusion and atomic structure.