Fabrication of metal-matrix composites by application of the superplasticity effect

The production of continuous-fiber metal-matrix composites (MMCs) with improved mechanical properties by solid-state consolidation under superplastic conditions was investigated. The finite-element method was used to model MMC consolidation, which was experimentally studied on a sample of boronaluminum composite. It was shown that the deformation properties of a matrix exert considerable influence on metal flow geometry and its strain-stress state. The superplasticity effect provides the straightening of a matrix flow front and the localization of an intense deformation zone. It also facilitates the removal of pores in the final stage of hardening and considerably decreases local stresses on the fiber surface. The features of matrix material flow during consolidation of composites were considered. It was shown that the matrix deformation during composite consolidation takes place in the form of cooperative grain-boundary sliding and intragranular sliding. The mechanism of matrix deformation determines a type of fiber-matrix reaction at the interface, or, alternatively, the type of fiber-matrix interface interaction depends on the intensity of localized deformation in the given area. Identification of the interface structure was performed by acoustic emission.