Acoustic relaxation in chromium

Measurements in polycrystalline chromium of the temperature and frequency dependence of the ultrasonic velocities from −65 to +60°C and frequencies of 5 to 35 Mc/s were made. The attenuation associated with the dilatational wave was measured at 15 Mc/s from −25 to +25°C. Anomalies in the attenuation and velocity for the dilatational waves were found at −19°C. The compressibility and Poisson's ratio were calculated and from these values the anomalous specific heat was determined. A dispersion in the dilatational velocity was found at −19°C, and, on the basis of a single relaxation process, the limiting high frequency velocity and relaxation time were estimated. From these calculations, a prediction of the magnitude of the attenuation was made and this agreed, within a factor of 2, with the measured attenuation.