EFFECT OF HEAT TREATMENT ON MECHANICAL PROPERTIES OF METAL MATRIX COMPOSITES

Abstract

The objective of this dissertation work is to discover the suitability of mixed salt route using stir casting technique to fabricate in-situ Al-4.5Cu-xTiB2 (x = 2.5, 5, 7.5 wt.%) composites. The in-situ TiB2 reinforcement particles were prepared by the exothermic reaction of K2TiF6 and KBF4 in molten aluminium alloy. The microstructure analysis of the cast composite was carried out to determine the shape, size and distribution of the TiB2 particles. The composite was then characterized for its mechanical properties and the effect of varying reinforcement concentration on the mechanical properties was studied. To further enhance the mechanical properties, T6 heat treatment was done. During the heat treatment process, the composite was solutionized at 540°C and holding for 2 hours then quenched in water. Thereafter, artificial aging (precipitate hardening) was done at 170°C for the duration of 5, 10, 15, 20, and 25 hours and its effect on the mechanical properties of the composite was recorded. In this study, an attempt to study the effect of varying reinforcement concentrations as well as the duration of aging on the mechanical properties of in-situ Al-4.5Cu-TiB2 composites has been made and it has been observed that as the percentage of TiB2 increases the peak aging time gradually reduces.