The density and interdiffusion coefficients of bismuth-tin melts of eutectic and near-eutectic composition

The method of gamma-raying of samples by a narrow beam of gamma radiation is used to investigate the temperature dependences of the density of bismuth-tin liquid alloys, which contain $30.0$, $44.0$, and $54.0$ at.$\%$ Bi, at temperatures from the liquidus line to $920$ K. The density jump in the case of solid-liquid phase transition is directly measured for the first time for an alloy of eutectic composition ($44.0$ at.$\%$ Bi). The temperature and concentration dependences of the thermal properties of the liquid Bi–Sn system are constructed. The kinetics of homogenization are studied of melts with average composition of $44.0$ and $54.0$ at.$\%$ Bi at temperatures from $550$ to $850$ K. The interdiffusion coefficients are determined from the results of these experiments.