The tensile properties of a particulate reinforced Al alloy in the temperature range-196-300 degrees C

The tensile properties of a particulate reinforced Al-Si-Mg alloy were determined in the temperature range - 196-300 degrees C. Microstructural coarsening of a peak aged (T61) material occurs at the higher temperatures (i.e. 200 and 300 degrees C), which, together with the test temperature, results in a considerable decrease in flow strength for both the composite and unreinforced alloy. However, the strengthening ratio (i.e. the ratio of composite to matrix strength, sigma(c)/sigma(m) actually increases with temperature. This effect is also observed when investigating the influence of test temperature alone (i.e. a stable matrix microstructure over the full temperature range). These results suggest that the primary relaxation mechanisms are damage accumulation and relaxation by plastic deformation of the matrix. There is no evidence of unrelaxed behaviour, even at - 196 degrees C, and the strain rate used during testing is likely to be too high to allow diffusional relaxation to be operative at the higher temperatures. Copyright (C) 1996 Canadian Institute of Mining and Metallurgy.