Calculation of Aluminum Equivalent Based on Thermo-Calc Software in Ti-Al-Nb Ternary System

Ti-Al-Nb ternary phase diagrams were calculated by Thermo-Calc software. The analysis of the calculated vertical sections of Ti-Al-Nb phase diagram indicated that when Nb content is fixed at 5at.% and Al content is lower than 52.3at.%, the primary phase would be β phase during solidification. With 10 at.%Nb and Al content lower than 55.8at.%, or with 15 at.%Nb and Al content lower than 56.9at.%, the primary phase would be β phase. The vertical sections of Ti-Al-Nb ternary phase diagram were further simplified into pseudo-Ti-Al binary phase diagram. According to the pseudo-Ti-Al diagram, the expression of the aluminum equivalent was obtained in Ti-Al-5Nb ternary alloys.