The oxidation behavior of Ni3Al-Zr alloys with various zirconium contents

The oxidation behavior of Ni3Al alloys with zirconium additions was studied after long-term air exposure over a temperature range of 560-1300 degrees C. The results showed that the penetration of oxides into Ni3Al-Zr alloys along the grain boundaries was caused by the formation of ZrO2. The penetration depth of the oxides increased with an increase of the zirconium content and oxidation temperature The reaction of the oxides was controlled by oxygen diffusion in allotropic ZrO2, and the lines in the Arrhenius diagram of the reaction rate constants reflected at 1050 degrees C. However, the penetration of oxides was not seen in the alloy without zirconium addition. Through electron probe microanalysis and X-ray diffraction, the compositions and structures of the oxides for these alloys were also determined.