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J. Phys. IV France
Volume 113, January 2004
Page(s) 85 - 90

J. Phys. IV France
113 (2004) 85
DOI: 10.1051/jp4:20040019

Shape memory alloys: From the physical properties of metastable phase transitions to dampers for civil engineering applications

V. Torra1, A. Isalgue1, F.C. Lovey2, F. Martorell1, F.J. Molina3, M. Sade2 and H. Tachoire4

1  CIRG-DFA-ETSECCPB-UPC C/. Gran Capità s/n, Campus Nord B-4, 08034 Barcelona, Spain
2  Div. Metales, CAB-Instituto Balseiro, 8400 S.C. Bariloche, Argentina
3  ELSA Laboratory, IPSC, EC-JRC, 21020 Ispra, ltaly
4  MADIREL/Thermochimie, UMR 6121, Université de Provence, Centre de Saint-Charles, 13331 Marseille Cedex 03, France

The physical properties of Shape Memory Alloys (SMA), useful in damping effects of scarce events as quakes, are studied for Cu-based alloys (CuAlBe) and partially for NiTi in the appropriate time scale. The evaluation of the deformation ( $\varepsilon$) in the hysteresis cycle and in their intemal loops, against the thermodynamic forces, i.e. the extemal stress ( $\sigma_{\rm ext}$) and temperature (T) is performed. The main goal for the applicability of the alloys centers in reliable behavior after several years of inactivity. The alloy require a minimal transformation temperature change and, also, within a reduced transient time to ensure that the material always remain inside the thermoelastic window (full parent phase recovery at zero stress and without permanent deformation at maximal stress). The macroscopic behavior associated with the Clausius-Clapeyron equation, the material fatigue and the local temperature changes, produced by latent heat and by frictional contributions, are critically visualized. The microscopic phenomena related with the transient after quenched effect, the evolution in the region of phase coexistence and the long time seasonal actions in parent phase are, also, evaluated.

© EDP Sciences 2004