Solidification of the eutectic Sn–43 mol % Bi alloy

Resumo

The processes of melting and solidification of the eutectic Sn–43 mol % Bi alloy are studied by cyclic thermal analysis. It is found that this alloy melts at a temperature T_L = 412 K (which corresponds to the reference melting temperature of the eutectic) upon heating and solidifies isothermally at a temperature T_S = 394 K upon cooling; that is, the temperature difference is ΔT_LS⁻= 18 K. A comparison of temperatures T_L and T_S reveals a temperature hysteresis (TH). The activities and the activity coefficients of tin and bismuth in the eutectic are calculated at temperatures T_L and T_S. The enthalpies of melting at T_L and solidification at TS are measured. The ways of changing the Gibbs energy during TH are determined.