2004 Volume 45 Issue 11 Pages 3163-3171
TiB2 particle reinforced Cu matrix composites were fabricated by a combustion reaction between Ti and B in a Cu-Ti-B system. Addition to the fabrication of the composite, its bonding with 1050 Al alloy were successfully carried out in a single-step process by using the high heat of the combustion reaction. When the combustion synthesis of Cu-50 vol%TiB2 was attempted, a minute quantity of unfavorable Cu3Ti was formed with TiB2 in the Cu matrix. However, for Cu-60 vol%TiB2, only fine TiB2 particles below 4 μm in diameter were formed in situ, and homogeneously distributed in the Cu matrix. Also for Cu-70 vol%TiB2, the combustion reaction occurred completely without forming any unfavorable phases, although some Cu was evaporated during synthesizing the composite. In a Ti-B binary system, any reaction was not generated in the temperature range from room temperature to 1473 K. However, in the Cu-Ti-B ternary system, the combustion reaction was generated near the melting point of Cu, suggesting that it was activated by molten Cu. Preheating before inducing the combustion reaction was effective in bonding with long Al rods and also in reducing bonding defects. Intermetallic compounds consisting of Al, Cu and Ti were observed with unreacted B in the bonded layer. For the bonded specimen with a Cu insert layer, a eutectic microstructure of Al and Cu was formed between the Al alloy and Cu insert, and unreacted B was observed with a compound of Cu and Ti between the composite and Cu insert. The bonding strength was improved by inserting the Cu layer and by preheating. The bonded specimen with no insert layer was fractured between the composite and the Al alloy. By inserting the Cu layer with preheating, the fracture occurred between the Al alloy and the Cu insert.
