Effect of Solution Treatment on the Microstructure of γ Precipitates in the ‎IN738LC Superalloy Before and After Aging

Nickel base superalloys are used for their unique properties in the construction of various components of ground and air gas turbines. In the present study, the IN738LC superalloy was solubilized at a temperature of 1090 ° C to 1200 ° C and at a time of 30 to 120 minutes. The samples were aged for 24 hours after solution heat treatment at 800 °C. Before and after aging, samples were examined by optical microscopes (OM), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The results showed that increasing the temperature and time of solution heat treatment reduces the volume percentage and the size of the g¢ precipitates, while the volume percentage and size of the g¢ precipitates are increased and decreased, respectively, after aging. Micro hardness tests showed that hardness of the superalloy was strongly influenced by the characteristics of sediments. By increasing the solubility time and reducing the volume percentage of g¢ precipitates, the hardness decreased and increased after aging.