Damping behavior in Al ₁₈B ₄O ₃₃w/Al composite containing an interfacial layer with low melting point metal particles

A SnO ₂·Bi ₂O ₃ coating was deposited on the surface of Al ₁₈B ₄O ₃₃ whiskers. A pure aluminum matrix composite reinforced by an Al ₁₈B ₄O ₃₃ whisker with SnO ₂·Bi ₂O ₃ 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 °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.