Damping behavior of Bi2O3-coated Al18B4O33 whisker-reinforced pure Al composite

A pure aluminum matrix composite reinforced by Al18B4O33 whisker with Bi2O3 coatings was fabricated by squeeze casting method. The damping behaviors of the coated composites are investigated. The introduction of Bi at the interface between whisker and matrix in the coated composite during squeeze casting process plays an important role in the improvement of damping capacity. The results of damping characterization indicate that the damping capacity of the coated composites strongly depends on the coating contents and vibration frequencies. The damping mechanisms of the coated composites have changed when the vibration frequency changed. The presence of a critical temperature in the damping-temperature curves of the coated composites has been found first when the vibration frequencies have changed. The critical temperature decreased with the increasing of coating contents. The dominant damping mechanisms are transferred from dislocation damping (below the critical temperature) into interfacial damping (beyond the critical temperature).