Investigation on room temperature damping vs strain amplitude behaviors of hypereutectic Al-17Si-xL

Effects of strain amplitude on the room temperature damping capacity of hypereutectic AlSixLa alloys at different frequencies (f=0.5Hz, 1Hz, 10Hz) were investigated. Experimental AlSixLa alloys were manufactured through conventional casting and spray deposition processing routines and their damping behaviors were studied using DMTA instrument. The results show that most of ascasted or asspray deposited hypereutectic AlSi alloys exhibit similar damping behavior (tg) vs. strain amplitude: with the increase of strain amplitude, damping experienced a incubation period initially; fast increase to a damping peak period then, and falling back again period at last. The different additions of La have small influence on the damping capacity of casting AlSi alloys except that the addition of 6wt% La addition obviously deteriorates the damping capacity. On the other hand, the damping peak of spraydeposited Al17Si alloy with the addition of La was evidently higher than that in Lafree Al17Si alloy. Damping capacities of spraydeposited Al17SixLa alloys were higher than their casted counterparts. The damping behaviors vs. strain amplitude of hypereutectic Al17SixLa alloys can be explained by GL dislocation model.