Fiber-spacing effects in the solidification processing of metal matrix composites

The effects of the presence and packing geometry of reinforcing fibers in a solidifying aluminum matrix are investigated. Particular attention is paid to the effect of changes in the fiber pitch on Me thermal field and thus o n the propagation of the solidification front. Results of simulations for b oth low- and high-conductivity (alumina and copper) fibers are presented. F or fibers in an in-line configuration, a critical fiber spacing is identifi ed: a fiber pitch smaller than this critical value causes increasing front distortion with each additional fiber that the front passes. When the fiber pitch is at or greater than the critical value, the solidification front h as a sufficient distance in which to return to an essentially planar shape. The critical fiber pitch for alumina and copper fibers is approximately 2. 5 and 2 fiber diameters, respectively. For staggered fibers, the behavior o f the propagating solidification front is more complex, and changes to the critical spacing due to fiber staggering are discussed.