Defornation mechanisms in the nanolamellar composite Cu-Nb

点击翻译按钮获取中文摘要

The plastic behaviour and microstructural stability of nanolamellar metallic composites are of paramount importance for practical applications since most of the beneficial mechanical properties are related to the diminished length scales (i.e. layer thickness, grain size in the layers) in the material. The model system Cu/Nb produced with different layer thicknesses of 1000 - 10 nm is chosen for investigations of the mechanical properties by tensile tests at low temperatures including 4 K tests. Based on temperature and strain rate change tests thermal activation analysis is used to determine the athermal influence of grain size (or rather layer thickness) on the total stress measured in the experiment allowing a precise analysis of the Hall-Petch relationship. Moreover, thermal activation analysis results in information about the elementary deformation mechanisms dominating the plastic behaviour of the material. Besides, there is interest in the influence of temperature on deformation localization through the development of micro and macro shear bands in the layers and across the layer boundaries. The extent and effects of deformation localization will be analyzed by electron microscopy.