Measurement by DMA in Tension of Elastic Moduli and Transformation Behaviour of fine Nitinol Medical Wires as function of Stress and Temperature
Résumé
In this work, thermomechanical tensile behaviour of thin NiTi wires was investigated by means of a non conventional device which combines a conventional tensile device with a Dynamic Mechanical Analyser (DMA). In this device, the displacement of the specimen upper extremity is controlled by a servo-motor with static drive while the displacement of the lower extremity is controlled by a shaker with dynamic drive. Tensile tests were performed over a wide temperature range (-100°C; 100°C). Wires containing nanograined microstructures were used in order to minimise plastic deformation. These tests are analysed to study dependencies of phase transformations (A-R, R-M and AM) on stress and temperature and to bring new information concerning the value of the elastic moduli in the different stress-temperature regions.
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