Production of namo-scaled multilayered materials produced by repeated press-rolling and formation of super high strength materials

Fe/Cr、Co/Cu和Co/Ag等多层膜表现出优异的巨磁电阻效应，并已通过良好控制的逐层沉积技术制备。代替逐层沉积方法，一种完全不同的样品制造方法，其利用反复压制或轧制，已被成功地开发并应用于从金属粉末和片材生产层状纳米有序结构。通过这种样品制备方法，可以以块体形式制备层厚度为纳米级的金属多层膜。本文利用这种尺寸的样品，研究了Fe/Ag和Fe/Cu多层膜的力学、磁电阻和热电性能，并成功地从宏观的金属片叠层出发，通过反复压轧制备了层厚为10- 20 nm的Fe/Ag和Fe/Cu多层膜。对于各种层厚度的样品测定。屈服应力和极限强度随层厚的减小而增大。屈服应力与层厚度的关系表现出所谓的Hall-Petch关系，反平方根依赖。

Multilayers such as Fe/Cr, Co/Cu and Co/Ag have exhibited excellent giant magnetoresistance and have been fabricated by the well-controlled layer by layer deposition techniques. Instead of the layer by layer deposition methods, a totally different approach of sample fabrication, which utilizes the repeated pressing or rolling, has been successfully developed and applied to produce the layered nanometer-ordered structures from metal powders and sheets. By this sample preparation method, it is possible to produce metallic multilayers with the layer thickness in nanometer order in a bulk form. In this work, taking advantage of such bulk dimension of the sample prepared, results of the exploration of the mechanical, magnetoresistive and thermoelectric properties were reported.Bulk Fe/Ag and Fe/Cu multilayers with layer thickness of 10-20nm have been sucessfully fabricated by repeated press-rolling directed from a macroscopic stack of metal sheets.The mechanical strength of thin foil starting samples, as measured by tensile tests, was determined for samples of various layer thickness. The yield stress and ultimate strength increased with decreasing layer thickness. The yield stress versus layer thickness showed so called the Hall-Petch relation, the inverse-square-root dependence.