The Effect of Time and Temperature of Solutionizing Heat Treatment on γ′ Characterization in a Ni-Base Superalloy

Nickel-base superalloys are being used widely in the air and land-based gas turbines. The primary strengthening mechanism of these alloys is the distribution of the gamma'(Ni-3 (Al, Ti)) intermetallic phase. This phase is formed in two stages, including the solutionizing and aging heat treatments. In order to create a structure with the desirable properties, the solutionizing heat treatment is more important than aging. In this research, solutionizing heat treatment was conducted at different temperatures and times, and aging heat treatment was carried out at a constant temperature of 850 degrees C for 24 h. gamma' precipitates characterization was done by scanning electron microscopy and field emission scanning electron microscopy. The results showed that the volume fraction and size of secondary gamma' precipitates decreases as the temperature and time of the solutionizing heat treatment increases. Therefore, after the aging, size and volume fraction of gamma' precipitates initially increased and then decreased.