In situ preparation of TiB2 reinforced Al base composite

Abstract

In situ formation of Al-TiB₂ metal matrix composite has been successfully fabricated through an exothermic reaction process. The base alloy used in the present investigation was Al-4 wt% Cu. It was first melted at 850°C. After that, two types of salts, namely, K₂TiF₆ and KBF₄ were added into the molten Al alloy by stirring. An exothermic reaction between the two salts and molten Al took place to form in situ TiB₂ particulates in the molten Al alloy. The exothermic reaction period was varied from a minimum 5 min to a maximum 35 min to investigate the relationship between the degree of reaction, the growth behaviour and the microstructures of TiB₂. After the reaction, the composite was cast into rods of 25 mm diameter. Both X-ray diffraction measurement and scanning electron microscope analysis revealed the formation of TiB₂. The amount of TiB₂ particulates increased when the exothermic reaction period was prolonged. Its microstructure was examined under optical and scanning electron microscopes.

Keywords:

• Kevwords: Metal matrix composites
• in situ TiB2
• microstructures
• grain refinement