Effects of manufacturing environments on the residual stresses in a SiC/Ti metal-matrix composite

A three-dimensional micromechanical finite element model is developed to study the effects of a manufacturing environment on thermal residual stresses in a SiC/Ti-6Al-4V metal-matrix composite. The model includes a representative volume element consisting of a quarter of SiC fiber covered by relatively thick coating and an interaction layer all of which are surrounded by the Ti-6Al-4V matrix. Stress relaxation due to the viscoplastic behavior of the matrix is accounted for different manufacturing environments, that is, air and nitrogen. The results show that the presented model provides accurate predictions when compared with experimental data. It is possible to use the presented results for appropriate selection of manufacturing parameters. The results suggest that to delay the onset of interface debonding, the best choice is to use cooling rates higher than 0.64 and 0.1 degrees C/s, respectively, for air and nitrogen environments. In order to use simple elastic-plastic models to predict residual stresses within the composite, detailed equivalent stress-free temperatures for various environments, cooling rates, and fiber volume fractions are presented.