Titanium alloy is employed in aerospace

aviation

navigation

and other fields because of its excellent comprehensive properties

such as high specific strength

strong heat resistance

excellent corrosion resistance

and good low temperature performance. However the high cost of titanium alloy seriously restricts its large-scale application. Based on Ti-6Al-4V alloy which has the best comprehensive properties

several Ti-Al-V-Fe alloys with different contents of V and Fe were designed under the guideline of using cheap alloy elements instead of expensive alloy elements. With the help of the stability factor Kβ

the stability of β phase and the effect of β stabilizing elements were analyzed. The calculation models for critical cell coefficients ofβstabilizing elements of quenched alloys and annealed alloys were established by theoretical derivation. On this basis

the calculation methods for volume fraction of α phase and β phase were established

and the theoretical calculation of the volume fraction of α phase and β phase in Ti-Al-V-Fe alloy was realized. Taking Ti-6Al-3V-1Fe alloy as an example

the theoretical volume fraction of α phase and β phase in the alloy was calculated. Then

Ti-6Al-3V-1Fe alloy ingots were prepared by vacuum non-consumable arc melting furnace. Samples were taken and heat treated. Finally

the volume fraction of α phase and β phase in the alloy was determined by X-ray diffraction. It was found that the measured results were in good agreement with the theoretical calculation results

indicating that the established model is feasible to predict the volume fraction of α phase and β phase.