INITIAL STAGES OF OXIDATION OF NI-BASED SINGLE- CRYSTAL SUPERALLOYS DURING HEATING IN RELATION WITH THEIR ISOTHERMAL OXIDATION KINETICS

摘要

The initial oxidation behavior of Ni-based single crystal superalloys at high temperature (1100 °C) was investigated. The heating-cooling oxidation curves of superalloys of different generations were analyzed using high precision thermogravimetry which is suitable for the accurate measurement of small mass changes occurring during short oxidation tests. The morphology of the oxide scales formed during the initial stages of oxidation, their chemical and phase compositions were analyzed. It was found that alloys forming an initial fast growing NiO or (Ni,Co)0 scale during heating did show the lowest isothermal oxidation kinetics.