The density and the binary diffusion coefficients of bismuth–indium melts
Rashid A. Khairulin, Sergei V. Stankus,Aleksandr V. Baginskii, and Vladimir A. Bityutskii
The density and the thermal expansion coefficients of liquid bismuth-indium alloys (16.09, 21.50, 33.33, 34.50, 37.50, 50.01, 52.73, and 73.87 at. % Bi) have been determined using γ-ray attenuation technique over the temperature range from liquidus line to 900 K. The experimental uncertainty of the density measurements is estimated to be within ±0.25 – 0.30%. The density changes during solid–liquid transition have been directly measured for the first time for Bi-In intermediate compounds and eutectics. The temperature and concentration dependences of the thermal properties for Bi-In system have been constructed. In particular, the concentration dependence of the molar volume of the liquid system weakly deviates from the law for ideal solution. The maximal value of excess molar volume is approximately 2.0·10-7 m3/mol at 50 at. % Bi and at 900 K.
Kinetics of homogenization of the melts with mean composition of 16.09, 21.50, and 73.87 at. % Bi has been investigated in the temperature range from 450 to 850 K. The measurement technique is based on direct registration of the evolution of composition profile in inhomogeneous liquid sample. The coefficients of binary diffusion D have been derived from these experiments. The experimental uncertainty of the D measurements is estimated to be within ±10%. The diffusion coefficients weakly depends on the composition and vary from 2·10-5 cm2/s at 450 K to 7·10-5 cm2/s at 850 K.
Keywords: Bismuth–indium alloys; melt; crystallization; density; thermal expansion; binary diffusion coefficient.