Damping peak and damping mechanism in Al18B4O33w/Al composite containing Sn and Bi interfacial phases at room temperature

Pure aluminum matrix composites reinforced with SnO2⋅Bi2O3-coated alumina borate whisker were fabricated by squeeze casting. The influence of vibration frequency on the damping capacities of the composites at room temperature was examined. Only when the vibration frequency is 50 Hz, a new damping peak in the composites has been observed, which could be ascribed to the dislocation mechanism. Moreover, the damping capacities of the composites are independent on the vibration frequency (below 30 Hz). However, the damping capacities of the composites increase with increasing frequency when the vibration frequencies exceed 30 Hz, and thermoelastic damping becomes the dominant damping mechanism.