J. Phys. IV France 05 (1995) C2-263-C2-268
Growth and Characterization of Shape Memory Cu-Zn-Al Single CrystalsP. Perin1, G. Bourbon2, B.C. Goo2, A. Charai1, J. Bernardini1 and Ch. Lexcellent2
1 Laboratoire de Métallurgie, URA 443, Faculté St. Jérôme, 13397 Marseille cedex 20, France
2 Laboratoire de Mécanique Appliquée, URA 004, Faculté des Sciences, 25030 Besançon cedex, France
To provide a better insight of shape memory alloys (SMA) behavior, Cu- Zn-Al single crystals were grown by the Bridgman technique. Melting was performed under pure argon in a graphite crucible allowing to obtain samples (total length 40 mm) with the final shape directly suitable for mechanical tests (cylinders with taper heads : 25 mm useful length, 4 mm in diameter). The chemical composition was checked by Differential Scanning Calorimetry and resistivity. It was found that a small zinc concentration gradient exists along the samples : it induces a difference less than 5 K for transformation temperatures in the useful length. The morphology, the shape deformation, crystal structure, sub-structure and orientation have been investigated by optical, transmission and scanning electron microscopy and by X-Ray diffraction. Pseudoelastic isothermal tensile tests and training under constant applied stress and variable temperatures were carried out. The training efficiency for these elaborated alloys is very large (about 80-90%).
© EDP Sciences 1995