非晶合金熔体的原子扩散

Atomic Diffusion in Amorphous Alloy Melts

非晶合金熔体的扩散是描述非晶合金熔体动力学行为的重要参数,不同于一般的金属熔体,非晶合金熔体的扩散行为具有自己独特的性质,如表现出典型的慢扩散和复杂的温度依赖关系等。由于技术、理论上的原因,目前无论是国内还是国际上,对非晶合金熔体扩散的研究尚处于不成熟的阶段。主要介绍了扩散系数的几种比较可行的测量方法,其中包括最近本课题组在传统长管法和切单元法基础上开发的滑动剪切技术,该技术能够有效消除加热阶段的扩散,是熔体扩散系数测量的方法的一项进步。同时,基于前人的测量技术和理论模型,对非晶合金熔体的扩散研究进行了系统的总结和讨论。目前能较好地描述一般熔体原子扩散的模型:Arrhenius关系、VFT方程、Tn关系、Darken公式及S-E关系,在非晶合金熔体中都表现出很大的局限性。尽管MCT理论能预言熔体原子扩散的动力学行为,且得到了实验证实,但是其自身亦存在一些难以克服的问题。

Diffusion in amorphous alloy melts is an important kinetic parameter to describe the properties in melts. Different from the normal alloy melts, the diffusion behavior of amorphous alloy melts tend to have their own unique properties, such as representing a typical slow diffusivity and a complex temperature dependent. But the researches on atomic diffusion are still at a preliminary stage whether in domestic or international study due to technical and theoretical difficulties. This paper mainly introduced some measurement techniques of the diffusion coefficient, including our self-designed sliding cell method, which combined the merits of the traditional long capillary method and the shear cell method, and ruled out the undesired atomic diffuse occuring in heating process. It＇ s concerned as an effective way to measure the diffusion coefficient. In addition, based on the diffusion results and models of the amorphous alloy melts, the diffusion research in amorphous alloy melts were summarized and discussed. As some good models to describe the diffusion behavior of the simple liquids, Arrhenius relationship, VFT function, T^n relationship, Darken equation and S - E relationship show a lot of limitations in amorphous alloy melts. At the same time, although MCT theory can predict the dynamics of glass forming liquids, which were confirmed by experiments and simulations, it also have some issues that are difficult to overcome.