Stir Casting of in-situ Al 6061TiB2 Metal Matrix Composite Synthesized with Different Reaction Holding Times

Abstract

Conventional casting of Aluminium (Al) Metal Matrix Composite (MMC) faces certain disadvantages such as non-uniform distribution of the reinforcement particles in the metal matrix, insufficient wetting of particles by the liquid metal and segregation of the reinforcement particles in the matrix phase resulting in poor tensile strength, low hardness and other inferior mechanical properties. These problems can be solved by an effective casting method viz. stir casting which promotes uniform distribution of the reinforcement particles in the matrix phase, good wetting of particles by the liquid matrix metal and improvement of tensile strength and hardness which are essential mechanical properties required for engineering applications in the fields of transportation, construction and aerospace. Aluminium is one of the light metals and its alloys are used for developing many metal matrix composites due to its favorable mechanical properties such as low weight, good corrosion resistance and high electrical and thermal conductivities etc. The strength and hardness of aluminium alloy can be increased by introducing TiB2, the reinforcement phase in the liquid aluminium alloy matrix at a temperature above its melting point. In the present study, an attempt was made to fabricate in-situ Al6061-TiB2 metal matrix composite by incorporating halide salts such as potassium hexaflurotitanate (K2TiF6) and potassium tetrafluroborate (KBF4) in the aluminium alloy melt at 850⁰C. In order to investigate the degree of in-situ reaction during the formation of Al6061-TiB2 metal matrix composite the melt was maintained at 850⁰C with different reaction holding times (RHTs).