Texture evolution in metals under mechanical stress: Application of a tensile stage on a laboratory X-ray system
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Texture evolution in metals under mechanical stress: Application of a tensile stage on a laboratory X-ray system J. te Nijenhuis, N. Dadivanyan and D.J. Götz PANalytical B.V., Lelyweg 1, 7602 EA Almelo, the Netherlands ABSTRACT The evolution of texture in copper has been studied in situ as a function of the applied mechanical stress. A uniaxial tensile stage was integrated onto a Eulerian cradle in a laboratory X-ray diffraction system, providing a platform for pole figure measurements on samples under an externally applied mechanical load. Thin strips of rolled copper were investigated at various stages of elongation. The pole figures were of good quality such that the orientation distribution function could be well determined. Changes in the orientation distribution function as a function of strain along the β-fiber could be clearly observed; the initial main component S is replaced by the Copper component at higher stages of elongation. INTRODUCTION Macroscopic properties of solid materials, such as metals and ceramics, are determined by the intrinsic material properties and the orientation of each of the crystallites in the sample. In general the crystallites are not distributed randomly like in an ideal powder specimen. In most cases a preferred orientation of the crystallites, so-called texture, is present. This preferred orientation is a result of the history of the manufacturing process. In materials research it is therefore not only interesting to study the final texture of a sample but also to follow the texture evolution during the formation or deformation processes. Knowledge of the evolution of preferred orientations provides valuable information in order to optimize the manufacturing and (de)formation processes. A well-known method to study deformation processes is recording the stress-strain curve of a sample. In this method the sample material is clamped between two vises and elongated by stretching it with a constant applied force. The relationship between the applied mechanical load and the amount of deformation (elongation) reveals the elastic and plastic characteristics of the material. During the deformation process the preferred orientation of the crystallites will change as a result of the applied mechanical stress. X-ray diffraction is a widely used technique to determine preferred orientations. Orientation distribution functions (ODFs) of worked pieces of material can be obtained from a set of measured pole figures. In practice often large equipment is required to deform worked materials, making it virtually impossible to investigate the stress-strain behavior and the texture evolution simultaneously. With the integration of a compact tensile stage onto a Eulerian cradle on a laboratory X-ray diffraction system we have investigated the possibility to measure pole figures in situ as a function of the elongation of the sample. In the present study we describe the first results of texture evolution studies on rolled copper samples.
EXPERIMENT Tensile tests Mechanical deformation studies have
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