Validation of computer models for the consolidation of metal—matrix composites

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