Al-TiC composite made by the addition of master alloys pellets synthesised from reacted elemental powders

Selcuk, C. and Kennedy, A. R. (2006) Al-TiC composite made by the addition of master alloys pellets synthesised from reacted elemental powders. Materials Letters, 60 (28). pp. 3364-3366. ISSN 0167-577X

Abstract

This study details a technique for forming TiC particles in an Al matrix, which is subsequently added to molten Al to produce a metal matrix composite. The structure and mechanical properties of the resulting composite have been investigated. The master alloy was made by reaction of Al, Ti and C elemental powders where the Al content was controlled to form, isolated, spherical, micron-sized TiC particles. The formation of isolated TiC particles, in conjunction with reaction in argon, ensured that the master alloy was incorporated into the melt without the need for stirring and dispersed to release individual TiC particles into the melt. The small size and good wetting of the reaction-derived TiC ensured a good distribution of particles in the cast billet and this uniform distribution was carried over into the extruded product. The strength and stiffness of a composite with 10 wt.% TiC addition, in the T6 heat treated condition, increased by approximately 20% compared to the equivalent un-reinforced 6061 alloy. The large increase is attributed the good wetting and hence strong interfacial bonding that is achieved between "clean" Al and TiC interfaces derived through reaction between elemental powders.