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Abstract
Bi- and trilayer composites of titanium aluminides (Ti–Al) and substoichiometric titanium boride (TiB0.6) have been fabricated from green compacts placed under pressure. Ti–Al blends with ratios of 3:1, 1:1, or 1:3 have been prepared by ball milling. Subsequent to the preparation of the precursor blends, plate-shaped green compacts of Ti–Al and Ti-B0.6 were pressed at room temperature. Green compacts were stacked in a layered geometry and were heated rapidly under a static pressure of about 10 bar. After the temperature reached 1300–1400°C, the Ti–Al and TiB0.6 phases were synthesized by the conversion of the reactants into the product phases (also known as “thermal explosion” processing) and simultaneously consolidated and joined under a pressure of 80–100 bar.
Scanning electron microscopy (SEM) examination showed that the Ti–Al layer was highly heterogeneous, and the extent of heterogeneity depended strongly on the respective elemental ratio of Ti to Al. Furthermore, the conversion from reactants to products was found to be determined by the overall heat available during the thermal explosion processing step. Unlike the Ti–Al, the TiB0.6 layer was more uniform; however, the combination of heat and pressure was found to be insufficient to fully densify the aluminide layer. These and other features of the layered intermetallic structures will be discussed.
