Glass-Fibre-Reinforced Aluminium Alloys Formed by Hot Extrusion: Part II: Heat-Treatment

Procedures for the heat-treatment of aluminium alloys (HE9 and HE30) reinforced with glass fibres were investigated. The fibre-reinforced composites were formed by the hot extrusion of pressed billets consisting of a mixture of alloy and glass powders.(the softening-point of the glass being below the extrusion temperature used, so that discontinuous glass fibres were formed in situ on extrusion). It was found that the composites failed to respond to the standard solution heat-treatment and artificial ageing .procedures for the alloys. This was shown to be due to the removal of magnesium from th~ metal matrix by reaction with the glass phase. A study was made of the kinetics of the glass/metal reactions occurring, and of the effect of time and temperature on the solution heat-treatment. Satisfactory response to heattreatment was obtained by adding excess magnesium to the billet.