Attenuation and Velocity of Ultrasound Near the Critical Point of Gallium-Bismuth

Abstract

<p>Attenuation measurements were performed on a liquid Ga-Bi mixture above its miscibility gap and at the frequencies 16.6, 25.5, 37.6 and 49.7 MHz. The attenuation measurements were made over a composition range from 0.20 to 0.75 weight-fraction Bismuth and in the temperature range 0.3 to 9.9°C above the critical temperature of the mixture. For a mixture at the critical composition, attenuation measurements were also made 27.2°C above the critical temperature. The velocity of sound was measured at 25.5MHz and at each of the above temperature and composition points. The critical temperature and composition of the Ga-Bi system have been determined to improve accuracy as 263.1°C and 0.60 weight-fraction Bismuth, respectively. The attenuation results have been tested against current theories and these theories have been subject to critical analysis.</p>