Internal friction peak and damping mechanism in high damping aluminium alloy laminate

摘要

A new aluminium alloy laminate characterized by high damping, corrosion resistance and weldablity was de- veloped. The laminate designed for required aforesaid functions was actually a composite material, which was made of two anti-corrosive layers (Al), two damping layers (ZnAl alloy) and one reinfocing layer (AlMg alloy) by hot rolling. The damping characteristics were studied and it was found that there was an internal friction peak at about 50deg.C on internal fraction vs temperature curve for the laminate. For this reason, the activation energy of the peak was calculated. The ori- gin and damping mechanism for this peak was researched by means of SEM, TEM, X-ray and DSC. It is considered that the peak is caused by the interaction between dislocations and point defects in damping layers (AlZn alloy). i. e. by the movement of dislocations dragging point defects under the action of thermal-activation. The laminate is remained at room temperature for a long time, it will weaken or even disappear with the restoration of the crystal microstructure and the re- duction of the dislocation density in ZnAl alloy layers. The mechanism of the peak is in conformity with that of the dislocation-induced damping.