Evaluation of interaction parameters in metallic solutions by the isoactivity method

The evaluation of interaction parameters of elements from isoactivity data is theoretically analyzed. Normally, the Wagner formalism is limited in the evaluation of interaction parameters from isoactivity data because the con dition of constant activity reduces the degrees of freedom of the studied s ystem. The consistency and discrepancy between the logarithm formula and so lubility equation are discussed. In theory, x(i) = 2N(i) in M-i-j melts und er the isoactivity of i becomes the critical condition of consistency and d iscrepancy between the logarithm formula and solubility equation. Experimen tal results show that a discrepancy exists between the two methods if exper imental data do not meet the condition of x(i) less than or equal to 2N(i). It is necessary to consider the possibility of the formation of compounds as x(i) > 2N(i) in the system M-i-j at isoactivity of i.