Damping behavior in Al18B4O33w/Al composite containing an interfacial layer with low melting point metal particles

A SnO2 center dot Bi2O3 coating was deposited on the surface of Al18B4O33 whiskers. A pure aluminum matrix composite reinforced by an Al18B4O33 whisker with SnO2 center dot Bi2O3 coatings was fabricated by squeeze casting method. Sn and Bi particles were introduced to whisker/Al interface during the squeeze casting, resulting in the formation of the Bi-Sn two-component eutectic. The effects of the coating contents on the damping properties of the coated composites at various temperatures, frequencies, and strain amplitudes were examined. The results of the damping characterization indicated that the damping capacity of the coated composites strongly depends on the coating contents, strain amplitudes and vibration frequencies. A damping peak at about 150 degrees C appeared in the coated composites, and the damping mechanism is related to the interfacial slip caused by the molten Bi-Sn eutectic. A critical temperature in the damping-temperature curves of the coated composites has been found for the first time when the vibration frequencies changed. The dominant damping mechanisms changed from the dislocation damping to the interfacial damping below and above the critical temperature, respectively. The critical temperature decreases with the increasing of coating contents. (C) 2011 Elsevier B.V. All rights reserved.