Interface reactions during preparation of aluminium-matrix composites by the sodium process

A process has been developed in which aluminium matrix composites, reinforced by either graphite or polycrystalline alumina (FP) fibres, are prepared by immersing the fibres sequentially in molten baths of sodium, tin, and aluminium. The experimental details of this process are presented, and the theory behind the process is explained. In essence, sodium wets the fibres, and is then reacted to form stable intermetallic compounds at the fibre-matrix interface; these compounds are then wetted by the aluminium. Composites with full theoretical strength can be prepared by means of this process if rayon-base graphite. Pan I graphite, or FP fibres are used. Composites containing an intimate mixture of two or more types of fibres are also possible.This research was Company funded.