The evaluation of stability of secondary phases in superalloys is of great importance because of its application under high homologue temperatures. The precipitation hardening Inconel 718 superalloy has high stress rupture and creep resistance, good LCF behavior and high corrosion resistance. Those properties can be obtained due to the high stable matrix based on Ni, Fe and Cr, as well as secondary phases promoters elements such as Ti, Al and Nb. This study aims to analyze the phase stability among a range of temperature from 500°C to approximately 1400°C. The thermodynamic modeling has a high importance to predict the behavior of alloys among equilibrium transition. The microstructure of the system was evaluated using Thermo-Calc software and the selected databases: SSOL4 and TTNI6. This analysis made possible the prediction of the phases presented, compositions and amounts. Results from SEM analysis were used to compare the results obtained, showing good coherence between them.