6533b826fe1ef96bd1284f7e

RESEARCH PRODUCT

Oxidation mechanism of the Inconel 601 alloy at high temperatures

subject

description

The Inconel 601 alloy oxidation was performed in air, in the temperature range 1000-1150 °C, during 90 h. Kinetic results show that the parabolic behavior is always followed in this temperature range. The Arrhenius plot of the kp values shows two different activation energies. Between 1000 and 1050 °C the activation energy is E a1 = 160 ± 10 kJ/mol. In the 1050-1150 °C temperature range a higher value is calculated E a2 = 252 ± 20 kJ/mol. The E a2 value and the X-ray diffraction (XRD) results and scanning electron microscope (SEM) energy dispersive X-ray spectroscopy (EDS) examinations are in accordance with a scale growth mechanism limited by a growing Cr 2 O 3 scale acting as a diffusion barrier. In the 1000―1050 °C temperature range the activation energy is lower and the structural analyses show that the oxide scale is not only composed of Cr 2 O 3 . Then, the oxide scale is composed of titanium oxides (TiO 2 and Ti 2 Cr 7 O 17 ) and chromia mixed together. A doping effect of the chromia scale by titanium can be envisaged. Our results also show the presence of some Mn 1.5 Cr 1.5 O 4 at the external interface. This external subscale spalls off easily during cooling afterthe highest temperature oxidation tests. Nevertheless, XRD results and SEM-EDS observations show that the Cr 2 O 3 scale remains very adherent on the substrate and can give a good oxidation protection.This good adherence can be related to the presence of a low amount of aluminum in the Inconel 601 alloy composition.