Effects of macroscopic defects on the damping behavior of aluminum and Zn-27 Pct Al alloy

A study was carried out on the influence of macroscopic defects on the damp ing behavior of commercially pure Al and Zn-27 pet Al alloy. The macroscopi c defects, pores, and graphite particulates with a size of 0.001 +/- 0.0005 in and volume fractions ranging from 19 to 94 pet were introduced into the structures by infiltration technology. It has been shown that pores or gra phite particulates can improve the damping capacity of commercially pure Al , due to the interaction between macro- and microdefects. Pores, however, s how no detectable effects on the damping behavior of high damping Zn-27 pet Al alloy. Similarly, graphite particulates have little effect on the dampi ng capacity of Zn-27 pet Al alloy at low temperatures and, on the contrary, make the transformation peak value of internal friction decrease. It is co nsidered that graphite particulate may repress the eutectoid transformation process of Zn-27 pet Al alloy.