Studies on Oxidation Behaviour of Cobalt-Based Superalloy 605

Alloy L605 is a cobalt-based superalloy finding applications in the production of several critical components in gas turbine engines. Different parts made of this alloy are used in the aerospace industry. It is meant for use at temperatures up to 980 °C, and applications involve different types of oxidising environments. It hence becomes imperative to establish a thorough understanding of the oxidation behaviour of the alloy at high temperatures. The present study deals with oxidation behaviour of the alloy in the temperature range 650–850 °C in laboratory air environment under cyclic loading conditions. In addition to thermogravimetry, X-ray diffraction and EDAX analysis of the oxidised surfaces were carried out to study the oxidation reaction. The alloy showed considerable weight loss at 850 °C; there was no perceptible weight change at 650 °C. The reaction zone was found to be rich in O, Co, Cr and Mn. The activation energy for oxidation was calculated; it appears that outward diffusion of Mn and formation of Mn-containing compounds at the surface influence the activation energy.