Fabrication of TiB2/Al composites by combustion synthesis of Al-Ti-B system

Abstract

Aluminum matrix composites reinforced with TiB2 particles which were synthesized in situ by a combustion reaction between titanium and boron were fabricated from powder mixtures of Al, Ti and B. The combustion reaction was generated in the compacted powder mixtures with and without preheating by an ignitor. The influences of a powder mixing ratio, porosity and preheating of the compacted reactant on the combustion reaction for the Al-Ti-B system were experimentally investigated. The aluminum matrix composites including 30 to 60 vol%TiB2 could be fabricated by the combustion reaction without preheating, but some macroscopic cracks were occurred in the composites except for the Al-50 vol%TiB2. The relatively large porosity and preheating before the combustion reaction were effective to the self-propagation of the combustion reaction and microstructure of the synthesized composites, especially in the low volume fraction of TiB2. The reaction between titanium and boron in the Al-Ti-B system was initiated after the melting of aluminum.