Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-301-C8-304
Damping Evolution During Precipitation in Al-Mg-Si AlloysC.Y. Xie1, R. Schaller,1, W. Benoit1 and C. Jaquerod2
1 Ecole Polytechnique Fédérale de Lausanne, Institut de Génie Atomique, 1015 Lausanne, Switzerland
2 Alusuisse Swiss Aluminium Ltd., Sierre, 3965 Chippis, Switzerland
Damping capacity and shear elastic modulus measurements have been carried out during precipitation in AlMgSi alloys. After the specimen has been aged at the temperature corresponding to the lowest thermoelectric power, both damping and elastic modulus increase comparing with the as-quenched state. The effect of strain amplitude was investigated in specimens aged at different temperatures. A critical strain amplitude, εc, has been observed. For strain amplitudes higher than εc, the damping capacity increases strongly with strain amplitude. In addition a relaxation peak appears around 420K after ageing. The strong damping-amplitude effect and the relaxation peak are attributed to the breakaway of the dislocation from the solute atoms at low temperature and to the dragging of these solute atoms by the dislocations at high temperature respectively.
© EDP Sciences 1996