Temperature dependence of the sound velocity and ultrasonic attenuation in liquid BiGa and BiSn alloys

Abstract

The temperature dependence of the sound velocity and ultrasonic attenuation in several liquid BiGa and BiSn alloys was determined by means of an ultrasonic pulse technique. The sound velocity is shown to be linear with temperature and parabolic with concentration in BiSn alloys, and in BiGa alloys in the miscibility region. This behavior indicates a correlation between the behavior of the electrical resistivity and of the sound velocity. A rapid gravitational separation was observed at 262°C for the critical composition in the Bi-43.77wt.% Ga alloy. Ultrasonic attenuation measurements permitted the accurate determination of the position of the interface (meniscus) between the separated liquid phases. The rate of motion of the meniscus as a function of temperature and composition was measured. The ultrasonic technique is shown to be useful for the accurate determination of phase diagram boundaries in systems with a liquid miscibility gap.