Characterization of microstructures and oxidation behaviour of Nb–20Si–20Cr–5Al alloy

Abstract Static oxidation in air was performed on Nb–20Cr–20Si–5Al alloy at high temperatures ranging from 700 to 1400 °C. Pesting occurred at 700 °C while internal oxidation took place at 1300 and 1400 °C where Al 2 O 3 initiated at the interface between NbCr 2 and Nb 9 Cr 3 Si 2 phases. Phases present were Nb 5 Si 3 , NbCr 2 , Nb solid solution and Nb 9 Cr 3 Si 2 depending on the temperature. The aluminium content on each of the phases was analyzed. Al content in Nb 9 Si 2 Cr 3 has been found to be as high as 5–6 atomic percent. SEM, EDS and XRD techniques were utilized in order to characterize the specimens.