Exothermic reactions in powder mixtures of Al, Fe and Si

Exothermic reactions in powder mixtures of Al, Fe and Si are investigated b y three common thermal analytical techniques in this work. The results show three stages in the synthesis of the ternary AlFeSi compounds when bulk sa mples of mass 3 g are used. These stages are melting, slow reaction and mas s reaction. It is concluded that the second stage of slow reaction is actua lly an overlap between the first and the third stages. When the sample mass is small, approximately 190 mg, the second stage is not detectable. For an even smaller sample of about 20 mg, even the third stage of mass reaction may not occur. Hence, the sample mass and the equipment used have an effect on the onset of the reaction and its apparent mechanism. (C) 2001 Elsevier Science B.V. All rights reserved.