High-temperature microstructural evolution and quantification for alloys IN740 and IN740H: comparative study

Abstract

Their microstructural evolution, at 750°C for times ranging between 3000 and 5000 h, has been investigated by means of scanning electron microscopy (FEGSEM), electron back-scattered diffraction (EBSD), energy dispersive X-ray (EDX) analysis and phase quantification. All the phases present in the two alloys were identified and quantified allowing comparison between the two microstructures, their evolution and stability. Particular attention is paid to gamma prime, η and G phase. The results obtained are used within a broader investigation whose aim is the improvement and further development of a predictive creep model based on continuous damage mechanics (CDM) which can forecast the alloy creep life.