In-situ stir cast Al-TiB2 composite: Matrix modification

Abstract

Elemental Ti and B powders were mixed and added to molten aluminum. At 1040 °C, in-situ TiB2 particles were produced through the Ti-B exothermic reaction with aluminum to produce the desired Al-TiB2 composite upon casting. When a 4.5 wt.% Cu was incorporated to form the Al-Cu matrix, increased nucleation of TiB2 particles led to improved mechanical properties which were reaped at peak aged condition. Both the tensile and yield strengths showed an increase of 48% as compared to the matrix of pure aluminum. Addition of ferro-silicon, Zn and KBF4 salt to the Al-Cu melt caused an additional increase in the intensity of TiB2. The increase in reinforcement, however, did not result in significant improvement in the mechanical properties of the composite. Modification of the Al matrix has led to a competitive nucleation of TiB2 with Al3Ti, with TiB2 being found mainly along the flakes of the Al3Ti.