J. Phys. IV France 11 (2001) Pr8-375-Pr8-380
Martensitic transformation in Ti-Ni-Cu shape memory wires broken by thermal cycling under constant loadC.J. de Araújo1, M. Morin2 and G. Guénin2
1 Departamento de Engenharia Mecânica, Universidade Federal da Paraiba, Caixa Postal 10069, Cep. 58109-970, Campina Grande - PB, Brazil
2 GEMPPM, UMR 5510 du CNRS, INSA de Lyon, 20 avenue Albert Einstein, 69621 Villeurbanne, France
In this paper, the physical properties of a Ti-45.0Ni-5.0Cu (%at) alloy are studied after failure (rupture) by thermal cycling under constant load between 75MPa and 350MPa. Transformation temperatures measured by electrical resistance (ER) change and DSC techniques show a good agreement in the virgin specimens, however this is not the case for the failed material. In addition, for wires broken under stresses until 125MPa, the DSC peaks becomes sharper than the ones measured with the virgin wires. In all cases, the relative change of ER associated to the martensitic transformation in the failed wires was higher than the value measured in the virgin material. These results are discussed essentially considering the role of the oriented defects and internal stresses created in the wires during thermal cycling under constant load.
© EDP Sciences 2001