High temperature deformation of a 6061 Al composite with alumina particulate reinforcement

摘要

An investigation was conducted to determine the high temperature deformation behavior of a 6061 Al composite reinforced with alumina particulates. The composite was manufactured using an ingot metallurgy technique and the creep properties were determined over five orders of magnitude of strain rate and at temperatures from 623 to 773 K. The experimental results indicate that both the apparent stress exponent and the apparent activation energy for creep are high but, by taking a threshold stress into account, it is demonstrated that the true stress exponent is close to 3 and the true activation energy is close to the value for diffusion of Mg in the Al matrix. The results suggest that creep is controlled by the visocus glide of dislocations in the matrix alloy. A direct comparison shows that this composite is less creep resistant than a 6061 Al alloy reinforced with 20 vol