Mechanical Properties of Nitrided Boron-Aluminum Composites

Abstract

The development of a submicron boron nitride coating for boron filaments has made possible the production of boron-aluminum com posites by a continuous casting technique. The tensile properties of aluminized boron filaments, as well as composite modules and tapes, fabricated by this liquid infiltration process are evaluated in this investigation. Tensile strengths up to 297 ksi were obtained for 65 volume percent nitrided boron-6061 aluminum alloy composite modules. Thermomechanical treatment in air of early 16-filament modules showed no degradation in strength after one hour at 1050°F, or 1000 hours at 570°F. Seven inches square panels, fabricated by diffusion bonding 20 mil diameter modules, exhibited longitudinal tensile strengths as high as 187 ksi and transverse strengths up to 15 ksi for fiber volume fractions of approximately 50 percent. The use of Ti cladding on aluminum-boron panel surfaces increased the trans verse strength to 33 ksi.