Dispersion and Blending of SiC (Silicon Carbide) Whiskers in RSP Aluminum Powders

摘要

Metal matrix composites (MMC's) of research quality are required to establish reliable relationships between material properties, composition, and processing parameters. Systematic variation of composition and consolidation parameters is necessary to determine their effect on composite mechanical and physical properties. To address the problems of material availability, lack of control of material processing parameters, and nonuniform whisker distribution, a program was instituted to develop a technique for producing a uniform blend of metal powders and whiskers for subsequent consolidation and characterization. An ultrasonic method has been developed for separating silicon carbide (SiC) whiskers in the clusters which are typically found in the as-received SiC whiskers made from rice hulls. The method has also been used to disperse the whiskers uniformly in a -325 mesh rapidly solidified (RSP) aluminum powder. Scanning electron microscopic examination of the separated whiskers and the whisker/aluminum powder blend indicate that the whiskers retain a high length to diameter ratio after processing. Fully dense compacts produced by hot isostatic pressing of the blend exhibit a uniform whisker distribution.