MODELING THE DENSIFICATION OF METAL-MATRIX COMPOSITE MONOTAPE

The consolidation of monotapes consisting of a layer of continuous aligned ceramic fibers embedded in a plasma sprayed metal or intermetallic matrix is becoming a preferred approach for the processing of high performance composite systems. We present a first model that enables prediction of the density (and its time evolution) of a monotape lay-up subjected to a hot isostatic or vaccum hot pressing consolidation cycle. Our approach has been to break down the complicated (and probabilistic) consolidation problem into simple, analyzable parts and to combine them in a way that correctly represents the statistical aspects of the problem, the change in the problems interior geometry and the evolving contributions of the different deformation mechanisms. The model gives two types of output. One is in the form of maps showing the relative density dependence upon pressure, temperature and time for step function temperature and pressure cycles. They are useful for quickly determining the best place to begin developing an optimized process. The second gives the evolution of density over time for any (arbitrary) applied temperature and pressure cycle. This has promise for refining process cycles and possibly for process control. Examples of the models application are given for Ti3Al + Nb, gamma TiAl, Ti6Al4V and pure aluminum.