The Comparison of the Microstructure and Hardness of Al-B and Al-Mg-B Composites

Aluminum base composite materials with variable properties which have been strengthened by AlB2 particles have been widely used. In this study, composites with variable properties of Al-5%B and Al-2%Mg-2%B which are produced through centrifugal casting are investigated as far as their microstructure and hardness are concerned. The microstructure of these composite were studied by using metallography. Also the vickers microhardness test was performed on the samples. The review of the results of the microstructure showed that the volume fraction within the composite particles has continuously changed and therefore produces a non-uniform microstructure with continuously varying properties. Particle separation of AlB2 towards the casting regions led to higher hardness in this region. The volume fraction of AlB2 particles in the studied composites showed a strong dependence on the presence of magnesium in the composite structure