Microstructure and Damping Behavior of Porous Gr/Al Composites Fabricated by Powder Metallurgy Step Sintering Process

Although porous aluminum (Al) possesses pore damping characteristics, its damping performance is still unsatisfactory, which limits its further application in vibration reduction and noise reduction. To address this issue, this study utilizes powder metallurgy technology to incorporate graphite (Gr) into porous aluminum. The porous Gr/Al composite prepared by this method has the characteristics of both lightweight and high damping. In porous Gr/Al composites, there exist not only a large number of closed‐cell type pores but also numerous Alp/Alp and Gr/Alp interfaces. The yield strength of the porous Gr/Al composites gradually decreases with increasing ammonium bicarbonate (NH 4 HCO 3 ) and graphite content. Damping tests indicate that both the internal friction (IF) values and the equivalent IF values of the porous Gr/Al composites increase as the ammonium bicarbonate and graphite content rise. At room temperature, the IF value of the Al–10Gr–10N sample is 72% superior to that of the Al–0Gr–10 N sample. At 250 °C, the IF value of the Al–10Gr–10N sample is 99.1% superior to that of the Al–0Gr–10 N sample. The synergistic enhancement effects of the high intrinsic damping characteristics of graphite, pore damping, and interface damping enable the porous Gr/Al composites to have favorable damping performance.