Response to thermal exposure of the mechanically alloyed Al/C powder blends

The present work was undertaken to investigate the response of the mechanically alloyed AVC powder blends to thermal exposure. Carbon was introduced into Al powders via high-energy ball milling and Al4C3 particles were precipitated with a subsequent heat treatment. Al4C3 precipitation starts in the solid state and accelerates after the aluminium matrix melts. This reaction produces a very fine dispersion of carbide particles in a wide temperature range in samples milled for at least 6 h. Relatively higher nucleation rates in these samples owing to a high density of lattice defects introduced during high-energy ball milling is responsible. The fine carbide particles thus produced resist coarsening below 750 degrees C, but undergo substantial coarsening at still higher temperatures. (C) 2007 Elsevier B.V. All rights reserved.