Materials Science Forum, Vol.426-4, 749-754, 2003
Microstructural changes in a Ni-based super-alloy induced by thermal treatment
It has been reported good mechanical performance, corrosion and oxidation resistance at high temperatures for many Ni-based super-alloys. They are used in the industrial applications where this excellent behavior at high temperatures is needed. The samples for this study were extracted from a used gas turbine rotor blade. Optical microscopy and SEM (Scanning electron microscopy) were used to study the microstructure of the samples before and after the different thermal treatments in a muffle furnace and in a Simultaneous Thermal Analyzer (STA). The STA studies showed an interesting behavior of the alloy with the thermal treatment, which included important changes in repetitive runs of the same sample. Three melting processes were identified and attributed to different phases in the sample. The original microstructure of the sample changed dramatically with the different thermal treatments. The EDS (Electron Dispersion Scattering) was used to identify and quantify the elements in the alloy. Heat capacity has been evaluated from room temperature up to 1400degreesC. Finally, the oxidative process at high temperatures was studied in different atmospheres.