热处理对356铝合金阻尼性能影响的研究

研究了热处理对 35 6铝合金的组织和阻尼性能的影响。结果表明 ,铸态变质组织由发达α相枝晶和α +β共晶体组成 ,其中硅相 β呈块状和短条状。经过 5 35℃保温 5h后水冷的固溶化处理 ,硅相基本变成了细小圆形质点相 ,而α相枝晶宏观组织变化不明显。在 15 0～ 2 5 0℃的温度区间内进行的时效处理对硅相形态和α相的宏观组织亦没有明显影响。 35 6合金铸态试件的阻尼值较低 ,仅为 5 .5 4× 10 -4。固溶并淬火态合金阻尼为 6 .4 7× 10 -4。对合金在 15 0℃下保温 4h后空冷的退火处理 ,阻尼增至 1.11× 10 -3 ,但当时效温度过高时 ,阻尼反而下降。 35 6合金的阻尼主要是位错阻尼引起的 ,即外加交变应力作用下的位错振荡耗能

Effect of heat treatment on the damping capacities of 356 aluminum alloy

The effect of heat treatment on damping capacities and microstructures of 356 aluminum alloy was studied. The results showed that the microstructures of as-cast 356 aluminum alloys modified with Ti were composed with α dendrite phase and α+Si eutectic, and the Si phase appears strip. The morphology of Si turned to be fine equiaxial after the alloy was heat-treated at 535℃ for 5 hours and quenched into ambient water. The heat treatment that aged at 150～250℃ had no obvious effect on the morphology and microstructures of the alloy. The damping capacities of as-cast and solid soluted 356 aluminum alloys are relatively low, and is 5.54×10 -4 and 6.47×10 -4 respectively. The damping capacities increased to 6.47×10 -4 after the solid soluted 356 alloy was aged at 150 for 4 hours and cooled in air. Whereas the damping capacity decreased when ageing temperature was higher than 150℃. The damping of 356 aluminum alloys is mainly arisen from dislocation movement, i.e. under applied cyclic loading, the dislocations in alloys would attempt to oscillate, which would lead to the dissipation of elastic strain energy.