Ultrasonic attenuation caused by Rayleigh scattering by graphite nodules in nodular cast iron

Longitudinal ultrasonic attenuation has been measured in a series of specimens of nodular cast iron. The frequency range used was in the Rayleigh region for scattering by the metal grains and the graphite spheroids. Rayleigh scattering proportional to the fourth power of the frequency was observed. When interpreted in terms of present scattering theories, the attenuation was found to be caused predominantly by the graphite particles. Quantitative agreement was achieved between theory and experiment.