The effect of chemical composition of Ti-0.4 Al α-titanium alloy (PT-1M alloy) on the phase transformation temperatures up to melting temperature has been investigated using ThermoCalc software. The possibility of appearance of Ti2N nitride, Tix(CN)-type carbonitride, and Ti2Fe-type intermetallic in the alloy structure in equilibrium state has been proved by thermodynamic calculations. It has been proposed the so-called aluminum equivalent (Aleq) for PT-1M alloy to analyze the effect of chemical composition on the phase transformation temperatures change. The following equivalents have been suggested:
Al
eq
Tβ
for
β
↔
(
β
+
α
)
−
transformation,
Al
eq
T
l
i
q
for
L
↔
β
−
transformation, and
Al
eq
Tsol
for
(
L
+
β
)
↔
β
−
transformation. It has been shown the linear correlation between the characteristic temperatures of phase transformations in the investigated alloy and the proposed aluminum equivalents.