Fracture Behavior of Shock-Loaded Boron-Aluminum Composite Materials

Abstract

The dynamic tensile fracture, or spall, of filament-reinforced metal- matrix composites was investigated by means of the thin flyer plate technique. Aluminum alloys, containing approximately 50 volume percent boron filaments arranged in two mutually perpendicular directions, were impacted normal to the plane of reinforcement. Geometric shock wave attenuation, caused by the filaments in a plasma- sprayed and diffusion-bonded 6061 matrix composite, gave rise to a threefold increase in the impact velocity threshold for spall over that of unreinforced 6061-T6 aluminum. A brazed 6061/713 matrix com posite spalled at an impact velocity slightly lower than the 6061-T6 alloy, this was related to filament-filament contact points and planes of weakness existing prior to impact. Spall failure and shock-induced filament damage appeared to be mutually independent, although the number of crushed filaments and the severity of filament damage tended to increase with impact velocity.