(AlNÂ +Â Mg2Si)/Mg composites in situ synthesis and scale effect of particulate on damping capacity

(AlN + Mg2Si)/Mg composites with uniform distribution of reinforcing particulates have been in situ synthesized and the scale effect of reinforcing particulates on damping capacity is investigated. The results show that at room temperature, composites reinforced with coarser particulates exhibit higher damping capacity compared with that reinforced with finer ones at low strain amplitude due to dominant contribution of plastic zone damping, while composites reinforced with finer particulates exhibit higher damping capacity at high strain amplitude and high frequency due to dominant contribution of dislocation damping. As temperature increases, the difference of damping capacity between composites reinforced with different size particulates reduces due to high damping capacity mainly arising from the grain boundary sliding and particulate-matrix interface.