DISLOCATIONS IN CONTINUOUS FILAMENT REINFORCED W NIAL AND AL2O3/NIAL COMPOSITES/

Continuous filament reinforced W/NiAl and Al2O3/NiAl composites (as-pr ocessed, annealed, and thermally cycled) have much higher dislocation densities than that of monolithic NiAl. These higher dislocation densi ties resulted from the relaxation of thermal residual stress, which de veloped during the cooling of the sample from elevated temperatures an d was caused by the difference in the coefficients of thermal expansio n between the matrix and the reinforcement. The dislocation density in the region adjacent to the matrix-filament interface was high and dec reased only slightly with distance from the interface in the 30 vol pc t composites. The as-processed and annealed composites exhibited a rat her homogeneous dislocation density in the matrix. After thermal cycli ng, these composites showed no large difference in the dislocation den sity and morphology. However, there were local regions of lower disloc ation densities. This difference was examined in relationship to filam ent fracture, surface matrix cracking, and degree of bonding.