VALIDATION OF COMPUTER-MODELS FOR THE CONSOLIDATION OF METAL-MATRIX COMPOSITES

Finite element method (FEM) simulation results were compared to experi mental observations to establish the suitability of advanced modeling techniques for the prediction of the consolidation behavior of continu ous fiber, metal-matrix composites. Two consolidation techniques were examined: hot isostatic pressing (HIP) of foil-fiber-foil layups and H IP of tapecast monotapes. In both cases, the matrix was the alpha-two titanium aluminide alloy Ti-24Al-11Nb (a/o), and the fibers were silic on carbide. Model predictions and accompanying experimental measuremen ts revealed the important effect of the interface friction-shear facto r on consolidation time for foil-fiber-foil layups. In addition, the p redicted consolidation times for the foil-fiber-foil method were found to be sensitive to small variations in HIP temperature and material f low properties such as the strain-rate sensitivity, especially for low consolidation temperatures. By contrast, predicted consolidation time s for tapecast monotape layups were relatively insensitive to the magn itude of the interface friction-shear factor. The kinetics of densific ation of the tapecast monotapes were well described using an FEM model incorporating a material-sensitive yield function and associated flow rule.