Inelastic Contact Deformation of Metal Coated Fibers

ÐMetal matrix composites (MMCs) can be synthesized by aligning metal coated ceramic ®bers in a shaped container and applying pressure at elevated temperatures. The high stresses created at the contacts between neighboring ®bers cause inelastic matrix ̄ow that ®lls inter®ber voids, reduces inter®ber separations and results in composite densi®cation. The rate of densi®cation depends on the contact's resistance to ̄ow. Current contact mechanics models are unable to adequately predict this resistance because they do not account for the e€ect of the (elastic) ®ber. Closed-form solutions for contact stress±displacement rate and contact area±strain relationships are used to describe metal coated ®ber blunting as a function of ®ber volume fraction, matrix material non-linearity (i.e. creep stress exponent) and ®ber packing geometry. The solutions contain two unknown coecients (c and F) which are evaluated using the ®nite element method. A simple model for the consolidation of coated SiC ®bers is developed in terms of the coecients, c and F. The model indicates that materials with a low creep stress exponent are more dicult to densify as the ®ber volume fraction increases whereas, perfectly plastic materials exhibit a relatively weak dependence on the ®ber volume fraction. # 1997 Acta Metallurgica Inc.