Prediction of the pore-closing kinetics during the consolidation stage of SiC unidirectional long fibers: titanuum alloy matrix composites

Abstract : Titanium-aluminium alloy matrix composites reinforced by long SiC fibers are considered as potential replacements for the conventional alloys used in aerospace applications for higher temperature service. A direct elaboration route of such composites is the hot uniaxial pressing of an assembly of metal foils stacked between uniaxial fiber mats. The kinetics of pore closing are studied through a finite-element simulation, the pressure boundary conditions, rigid-fiber rheology, sticking friction between the matrix and the fibers and a two-domain rheological constitutive equation (modelled by two Norton-Hoff laws) corresponding to both superplastic and high strain-rate behaviour ranges for the Ti-6Al-4V alloy, being considered. The influence of the distance between the fibers for two types of arrangement (rectangular and triangular) is studied. The effects on the kinetics of pore closing of both consolidation pressure and rheological laws are discussed also.