On the role of process parameters of aluminothermic reaction synthesis of in-situ Al -TiB2 composites: microstructure and mechanical properties

S. Madhavan, Balasivanandha Prabu S. -, K.A. Padmanabhan


This is an account of a process that has led to an application for a patent of relevance to the metal cutting industry and the paper examines the scientific aspects like the influence of process parameters of aluminothermic reaction synthesis of in-situ Al/TiB2 metal matrix composites on their microstructure and mechanical properties. The reaction between the salts potassium fluoborate (KBF4) and Potassium hexafluorotitanite (K2TiF6) in the aluminium melt leads to the formation of TiB2 particles. The process parameters of reaction time (Rh), reaction temperature (Rt) and weight percentage of precursors (W) were carefully controlled in order to regulate the volume fraction of TiB2 formation in the aluminium melt. Detailed microstructure analysis at different processing conditions revealed that particle clustering was present in the reinforcement and that this changes the hardness and density of the resultant composites. Addition of cryolite, which is a surface-active salt, prevented agglomeration and emulsification at high temperatures and also facilitated the uniform distribution of the particles in the matrix. The prepared Al-TiB2 composites were tested for their tensile properties, density and hardness. Both hardness and yield strength are found to increase with an increase in the percentage of reinforcement. The percentage elongation decreases due to an increase in TiB2 ceramic particle content in the matrix. It is found that the reaction time plays a major role in TiB2 growth and the distribution of TiB2 particles within the matrix.

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