COMPATIBILITY OF VAPOR DEPOSITED B, SIC, AND TIB2 FILAMENTS WITH SEVERAL TITANIUM MATRICES

Abstract
The filament-matrix compatibility was evaluated for B, SiC, and TiB2 vapor deposited filaments with high purity, commercial purity titanium, and Ti- 6Al-4V. Filament-matrix diffusion sandwiches were prepared by solid state resistance bonding. These samples were subsequently heated at 800-991C for times of 1-100 hours. The reaction rates and reaction products were evaluated using light microscopy, electron replicas, microhardness measurements, and microprobe analysis. The order of decreasing filament-matrix interaction was B, SiC, and TiB2 in each of the three materials. High purity Ti, commercial purity Ti, and Ti-6Al-4V is the order of decreasing reactivity with the filaments after 100 hours at 850-991C. The reaction of B with unalloyed titanium is characterized as the formation of a TiB2 layer adjacent to the filament with an external acicular TiB layer. The reaction layers were formed by the predominately outward diffusion of the boron as evidenced by the lack of recession of the initial filament diameter and the void formation in the filament. The interaction of B with Ti-6Al-4V is characterized by the formation of TiB2 with the rejection of Al ahead of the advancing TiB2 front which stabilizes the alpha-titanium phase around the TiB2 reaction layer. The SiC filament reacts with titanium to form a multi-phased reaction layer. The SiC-Ti interaction takes place by the simultaneous growth inward and outward of the reaction zone. A uniform distribution of 0.1 weight percent titanium was observed in the SiC filament after 100 hours at 850C. The TiB2 filament reacted with titanium to form a TiB layer adjacent to the filament.

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