Effect of Minor Third Components on Metastable Immiscibility Boundaries of Binary Glasses

An equation was derived which relates the change in the metastable immiscibility temperature, Δ T m , caused by a minor third component and the corresponding liquidus temperature change, Δ T l . This relation is expressed as image where T m and T l are the initial immiscibility temperature and liquidus temperature, respectively, S is the entropy of binary liquid, and ΔS is the change in the configurational entropy. For a qualitative estimate, the relation ΔT m ∼Δ T l is satisfactory. To evaluate the above equation quantitatively, the entropy must be known. The entropy equation of Charles based on the number of nonbridging oxygen pairs and bridging oxygen atom was used and a reasonable estimate was made of the change of the immiscibility temperatures for selected systems.