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

点击翻译按钮获取中文摘要

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.