Hot deformation and processing maps of a particulate-reinforced 6061+20% Al2O3 composite

The mechanical behaviour of a particulate-reinforced composite 6061 + 20% Al2O3 produced by ingot metallurgy was investigated with compression tests at different temperatures and strain rates to evaluate the activation energy and to calculate the constitutive equations. The tests were performed in the temperature range between 350 and 500degreesC and at strain rates between 10(-1) and 10(-3) s(-1). The compression flow curves exhibited an initial sharp increase with strain, followed by monotonous hardening. The maximum stress decreased with decreasing strain rate and increasing temperature. The activation energy of deformation was 155 kJ mol(-1), close to the activation energy for self-diffusion in Al. The processing maps were calculated to evaluate the efficiency of the forging process in the range of temperatures and strain rates investigated and to recognise the instability zones of flow behaviour. Scanning electron microscopy observations on polished samples demonstrated damage development in conditions of plastic flow instability. (C) 2002 Elsevier Science B.V. All rights reserved.