高阻尼铝合金层压板的内耗峰及其阻尼机制

Internal Friction Peak and Damping Mechanism in a High Damping Aluminium Alloy Laminate

研制了一种新型铝合金层压复合板 ,它具有高阻尼、耐腐蚀和可焊接特性。这种材料是由两层纯Al、两层ZnAl合金和一层AlMg合金经热轧制成的复合材料。该材料在 5 0℃附近有一内耗峰 ,当材料在常温下停放 1年后 ,该峰消失 ,材料的常温阻尼能力随之降低。计算了该峰的激活能 ,并通过SEM、TEM、X ray和DSC等手段 ,对该峰的起因和阻尼机制进行了分析。认为 ,该峰是由层压板中ZnAl合金层引起的 ,是在热激活条件下由位错拖曳点缺陷运动所致。层压板在常温长时停放过程中 ,由于晶体回复 ,位错密度降低 ,导致该峰逐渐减弱直至消失。此峰符合位错诱生阻尼机制。

An aluminium alloy laminate is developed which is characterized by high damping, corrosion resistance and weldability. The laminate is a kind of composite material which is made of two anti corrosive layers (Al), two damping layers (ZnAl alloy) and one reinforcing layer (AlMg alloy) through hot rolling. The damping characteristics of the laminate is investigated and it is revealed that there is an internal friction peak at about 50℃ in curves of internal friction vs temperature. The activation energy of the peak was calculated. The origin of the peak and the damping mechanism is 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. the movement of dislocations dragging point defects under the action of the thermal activation. During the remaining of the laminate at normal atmospheric temperature for a long time, the peak will weaken and even disappear with the restoration of the crystal microstructure and the reduction of the dislocation density in ZnAl alloy layers. The mechanism of the peak is in conformity with that of the dislocation inducted damping.