Calorimetric study of 6061-Al-15 vol.% SiCw PM composites extruded at different temperatures

The precipitation kinetics of 6061-Al-15 vol.% SiCw PM composites consolidated by hot extrusion at three different temperatures have been studied by means of differential scanning calorimetry (DSC). The results have been analyzed on the basis of the Kissinger method and the Johnson-Mehl-Avrami model. The differences in the precipitation behavior result from the change in the effective activation energy for diffusion of Si in Al, if it is considered that this is the controlling process for the growth of precipitates. These differences are interpreted in terms of different dislocation densities. The contribution of Si diffusion along dislocations decreases the effective activation energy as the dislocation density increases. In this manner, values of the dislocation density for all the materials have been calculated.