Thermodynamic calculation for precipitation hardening steels and titanium aluminides

Thermodynamic calculation using Thermo-Calc was carried out to quantify the phase fraction and element partition in precipitation hardening steels and γ-TiAl based alloys. Calculations show that the precipitates formed in Fe–Ni–Al–Mo systems and PH13-8 stainless steel are NiAl phases, in accordance with atom probe microanalysis. Calculations of the phase constitution and element distribution in several titanium aluminides show again a good agreement with the experimental measurement from atom probe. In addition, Thermo-Calc calculation can help identify the existence of some phases which were not readily observed experimentally. It can be used as a guide in alloy design, especially the design of the γ-TiAl based alloys.