An experimental study on thermodynamics of the Cu-Fe-As and Cu-Fe-As-RE liquid solutions

By the method of the equilibrium vapor saturation there was determined the arsenic activity in the liquid diluted Cu-Fe-As and Cu-Fe-As-Mischmetal all oys a the temperature 1823 K. The measurements were carried out for the fol lowing concentrations of components: arsenic from x(As) = 0.008 to x(As) = 0.23; Mischmetal from x(Ce) = 0.0059 to x(Ce) = 0.036; iron from x(Fe) = 0. 05 to x(Fe) = 0.016. The Cu-As alloy was accepted as the reference mixture, where the activity coefficient of arsenic was described by the R e d l i c h - K i s t e r equation. The arsenic activity coefficient in the Cu-Fe-As and Cu-Fe-As-Mischmetal alloys were described by the Wagner equation and t he interaction parameters in both alloys were determined by the least-squar es method. In the Cu-Fe-As alloy epsilon (Fe)(As) = -2.7, and in the Cu-Fe- As-Mischmetal alloy epsilon (Fe)(As) = -3.5 and epsilon (Ce)(As) = -25.36. The calculated epsilon (Ce)(As), which has a significant negative value mea ns, that lanthanides strongly interact with arsenic and decrease the arseni c activity in cooper alloys.