Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-413-C8-416
Internal Friction and Young Modulus Behaviour of Hot-Rolled Cu-Al-Ni-Ti Shape Memory AlloysE. Cesari, C. Seguí, J. Pons and F. Perelló
Dept. Física, Universitat Illes Balears, Campus, 07071 Palma de Mallorca, Spain
The internal friction (IF) and modulus behaviour during thermoelastic martensitic transformation in grain refined Cu-Al-Ni-Ti shape memory alloys hot rolled at 650°C and 850°C has been studied using a three-point bending Dynamical Mechanical Analyser. In both alloys, Ti-rich X-phase particles, µm sized, are formed and inhibit grain growth. Lower IF peaks and modulus minima have been observed in the samples rolled at 650°C, which is related to the presence of micrometric γ2-phase particles. During ageing at 250°C, a decomposition process in the form of a fine dispersion of precipitates with sizes of a few nm after 50-80 hours ageing has been observed, together with a progressive reduction in the IF peaks and modulus minima of the martensitic transformation. These reductionsare attributed to a loss of mobility of the parent/martensite interfaces in a oscillating stress cycle caused by the precipitates.
© EDP Sciences 1996