AN EDDY-CURRENT TECHNIQUE FOR THE MEASUREMENT OF CONSTITUENT VOLUME FRACTIONS IN A 3-PHASE METAL-MATRIX COMPOSITE

An eddy current technique is developed for the measurement of reinforcement and intermetallics concentrations in extruded particulate-reinforced metal-matrix composites. The technique employs a theoretical conductivity model which accounts for the constituent phases, together with a measurement of two anisotropic conductivities on the composite, for determining the reinforcement and intermetallics volume fractions. Towards implementation of this technique, an analytical model is described which relates the anisotropic conductivities of extruded particulate-reinforced composites to their microstructures. The volume fractions were calculated using eddy current measurements made on a wide range of silicon carbide particulate (SiCp) reinforced aluminum matrix composite extrusions. The calculated values are shown to be in good agreement with the actual metallographically measured volume fractions of the reinforcement and intermetallics. The technique may be adopted for an on-the-fly assessment of product quality in a processing environment.