Determination of thermodynamic interaction parameters in solid V-Ti alloys using the mass spectrometer

The Knudsen effusion method was combined with a mass spectrometer sensing technique in order to measure thermodynamic quantities of solid solution alloys of V-Ti binary system. The technique makes use of the regular solution model in order to treat the vaporization data in terms of ion current ratios obtained from the mass spectrometer. Within the experimental temperature range of 1500° to 1725°C and the composition range of 0.10 <N _Ti<0.90, the activity of titanium in the bcc (β) phase relative to pure titanium for the binary alloy is:RT lna _Ti=RT lnN _Ti+N _V ² (1.82±0.13) kcal per g-atom while the activity of vanadium is:RT lna _V=RT lnN _V+N _Ti ² (1.82±0.13) kcal per g-atom. The experimental result on the pairwise interaction parameter agrees well with the theoretically calculated value.