Effects of macroscopic graphite particulates on the damping behavior of Zn-Al eutectoid alloy

The objective of present work is to investigate the effect of macroscopic graphite (Gr) particulates on the damping behavior of Zn-Al eutectoid alloy. The damping behavior of the Zn-Al/Gr is characterized by internal friction (IF). Macroscopic graphite particulates sizes are on the order of a millimetre (0.5-1.0 mm) and in large proportions, typically high 63 vol.%. The IF was measured on a multifunction internal friction apparatus (MFIFA) at frequencies of 0.5, 1.0 and 3.0 Hz over the temperature range of 25 to 400 degrees C, while continuously changing temperature. The temperature spectrums of IF are studied in a macroscopic graphite particulates reinforced Zn-A1 metal matrix composite (MMC) prepared by air pressure infiltration process. The damping capacity of the Zn-Al/Gr MMC, with two different volume fractions and sizes of macroscopic graphite particulates, were compared with that of unreinforced Zn-Al eutectoid alloy specimen. The damping capacity of the materials is shown to increase with introducing macroscopic graphite particulates. Finally, the operative damping mechanisms in the macroscopic graphite particulate-reinforced Zn-Al eutectoid alloy composite were discussed in light of IF measurements. (c) 2007 Elsevier B.V. All rights reserved.