Abstract
The effect of graphite particles on the damping behavior of 6061 Al-graphite composites was investigated with an aim to develop a high damping, stiffness, and hardness material. The composites were processed by mixing 6061 alloy powder with graphite particles, hot pressed as a billet and consolidated by reciprocating extrusion 10 times. The results showed that the graphite particles were greatly refined and uniformly distributed in the matrix. The graphite in situ reacted with the Al matrix to form fine dispersed Al 4 C 3 particles during both reciprocating extrusion and subsequent solution treatment. The Al 4 C 3 phase could result in a pronounced dispersion strengthening effect. The damping capacity of the composite increased with increasing graphite content. The composite showed a peak in damping capacity during aging treatment. The 6061 Al-20% (graphite, Al 4 C 3 ) composite solution-treated for 24 h and peak-aged displayed an excellent combination of damping capacity, stiffness, and hardness. The composite retained high damping while maintaining a high modulus because of the coexistence of graphite and Al 4 C 3 . The operative damping mechanisms, including intrinsic damping of graphite particle, interface damping, dislocation damping, and grain boundary damping, are discussed with consideration of material microstructure.