J. Phys. IV France 05 (1995) C2-459-C2-464
Thermomechanical Behaviour of Monocrystalline Cu-Al-Be Shape Memory Alloys and Determination of the Metastable Phase DiagramA. Hautcoeur1, A. Eberhardt2, E. Patoor2 and M. Berveiller2
1 IMAGO S.A., ZI Athélia I, Bât. Delta, 13600 La Ciotat, France
2 Laboratoire de Physique et Mécanique des Matériaux, Institut Supérieur de Génie Mécanique et Productique, Ile du Saulcy, 57045 Metz cedex 1, France
Stress-strain behaviour of monocrystalline Cu-Al-Be alloy was investigated by uniaxial tensile tests in a temperature range between -70°C and +160°C. Four kinds of typical behaviours were examined in this study.
Main interest was the determination of the σ-T diagram obtained from the σ- ε curves. This metastable phase diagram is comparable to the Cu-Al-Ni one.
Isothermal mechanical cycling was made at 6% strain up to 1500 cycles. As a result, a deterioration of the superelastic behaviour was found. A thermal flash allows to partially recover this behaviour. Rupture tests performed at a temperature above 120°C have shown the critical stress above which either brittle fracture of α' martensite occurs or plastic deformation of β phase takes place. Finally, comparative tests have been made between a single crystal, a polycrystal with small grains and a polycrystal with columnar structure (bamboo-type).
© EDP Sciences 1995