Effect of Fe Addition on the Activity Coefficient of Si in Cu-Fe-Si Melt at 1 623 K

摘要

The activity coefficient of Si in Cu-Si alloy and Cu-Si-Fe alloys was determined using three principles at 1 623 K. Cu-Si(-Fe) alloys at a low Si concentration were equilibrated with SiO_2 in a graphite crucible under a controlled CO partial pressure. Cu-Si(-Fe) alloys at a medium Si concentration were equilibrated with SiC in a graphite crucible. And finally, Cu-Si(-Fe) alloys at a high Si concentration were equilibrated in a Si_3N_4 crucible under a controlled partial pressure of N_2. The activity coefficients of the alloys were calculated based on the equilibrium Si concentration. The results show that the activity coefficient of Si in Cu-Si-Fe alloy decreases with an increase in the concentration of Fe. The results were evaluated in terms of the interaction parameters in molten Cu for Wagner's formalism, and the interaction coefficient in the concentrated solution. The evaluated thermodynamic properties of Cu-Si-Fe alloy indicated that the addition of Fe to Cu-Si alloy is effective in decreasing the activity of Si in the alloy.