Calculation of activity coefficients for components in ternary Ti alloys and intermetallics as matrix of composites

Based on Kohler's ternary solution model and Miedema's model for calculating the formation heat of binary solution, the integral equation was established for calculating the activity coefficients in ternary alloys and intermetallics. The activity coefficients for components in alloy Ti-5Al-2.5Sn, Ti-6Al-4V and intermetallics TiAl, Ti₃Al and Ti₂AlNb were calculated with the equations. The calculated data coincide well with the experimental ones found in literatures. According to the calculated activity coefficients and activities, it can be predicted that the interfacial reaction in SiC/Ti₃Al composite is more severe than that in composites SiC/Ti₂AlNb and SiC/TiAl.