Development of a biaxial tensile module at synchrotron beamline for the study of mechanical properties of nanostructured
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Development of a biaxial tensile module at synchrotron beamline for the study of mechanical properties of nanostructured films E. Le Bourhis1, B. Girault1, P.-O. Renault1, P. Goudeau1, G. Geandier2, D. Thiaudière2, R.N. Randriamazaoro3, R. Chiron3, D. Faurie3, O. Castelnau3 1
LPM-PhyMat, UMR6630 CNRS, Université de Poitiers, B. P. 30179, 86962 Futuroscope, France 2 Synchrotron SOLEIL, L'Orme des Merisiers, BP 48, 91192 Gif sur Yvette, France 3 LPMTM, UPR 9001 CNRS, Université Paris-Nord, 93430 Villetaneuse, France ABSTRACT We have developed on the DIFFABS-SOLEIL beamline a biaxial tensile machine with synchrotron standard for in-situ diffraction characterization of thin polycrystalline metallic film mechanical response. The machine has been designed to test cruciform substrates coated by the studied film under controlled applied strain field. Technological challenges comprise the fixation of the substrate, the generation of a uniform strain field in the studied (central) volume, the operations from the beamline pilot. Tests on W and W/Cu multilayers films deposited on polyimide substrates are presented. INTRODUCTION Understanding the mechanical behavior of nanostructured thin films in relation to their microstructure, in particular to the grain size, is of utmost importance for the development of technological applications [1]. Synchrotron X-ray sources allow for characterizing small volumes of material in an acceptable time schedule. Hence, supported thin films mechanical response has been characterized experimentally in situ by synchrotron X-ray diffraction [2,3] while having in view their microstructure. This is particularly important when the films are multiphased and/or formed by anisotropic elastic crystallites. In such case, when the crystallites are not randomly distributed (for instance in the presence of texture) the film response is expected to be elastically anisotropic. The tests are generally carried out under uniaxial loading, the films being stressed biaxially because of the Poisson ratios mismatch (between the film and substrate). The transversal component of stress is then imposed by the deposited film properties. So far, it is of utmost importance to control both stress components. In that objective we have developed a biaxial loading machine at synchrotron standard allowing for applying in plane normal forces to coated substrates. Experiments on the elastic deformation of isotropic W and on the confined plasticity and fracture of W/Cu multilayers are presented. BIAXIAL TENSILE MACHINE DESIGN The tensile machine has been designed to allow for loading along two normal axis cruciform substrates coated by the studied films. The device is to be operated on a beamline at SOLEIL standard (French synchrotron at Gif sur Yvette, France). A micrograph taken at
DIFFABS beamline and a schematic representation of the machine are shown in Figure 1. The machine is compact 3.5 kg in weight, 19x19x8.5 cm3 in size with an empty centre and is designed to allow X-ray diffraction under small angles (n
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