NONDESTRUCTIVE EDDY-CURRENT EVALUATION OF ANISOTROPIC CONDUCTIVITIES OF SILICON-CARBIDE REINFORCED ALUMINUM METAL-MATRIX COMPOSITE EXTRUSIONS

Nondestructive eddy current methods were used to evaluate the electric al conductivity behavior of silicon-carbide particulate (SiC(p)) reinf orced aluminum (A1) metal-matrix composite extrusions. The composites investigated included 2124, 6061, and 7091 A1 base alloys reinforced b y SiC(p). The composite extrusions exhibited anisotropic conductivitie s with the maximum conductivity occurring along the extrusion plane. M icrostructural characterization showed that the observed anisotropic c onductivities could result from the preferred orientation distribution of SiC(p). A theoretical model was formulated to quantify the influen ce of composite constituents (SiC(p), intermetallics, and A1 base allo y) on the anisotropic conductivities of the composites. The theoretica l predictions of conductivities were found to be in good agreement wit h the experimental results.