Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-433-C8-436
Internal Friction Measurements During Stress Induced Martensitic Transformation of Cu Zn Al Shape Memory Single CrystalM. Perez and M. Morin
GEMPPM, UMR C5510, INSA de Lyon, Bât. 502, 20 av. A. Einstein, 69621 Villeurbanne cedex, France
The shape memory alloys present, in the high temperature phase, a super-elastic behaviour : during a super-elastic test, the martensitic transformation is induced by the stress, and a large reversible deformation is observed. With a single crystal, the maximum superelastic deformation reaches 8 to 10%. During the tensile test on a single crystal, only one variant of martensite is induced in the shape of many parallel needles. Using a specific tensile machine, we have measured the friction due to the movement of the interfaces between the austenite and the martensitic phases. These measurements have been realised during a tensile test on single crystals of CuZnAl. The movement of the interfaces is obtained by a low sinusoidal stress that is superimposed to the tensile stress. Results show that the interfaces are progressively pinned when the super-elastic strain is maintained constant. This pinning disappears when the strain is slightly increased.
© EDP Sciences 1996