Microscopic Investigation of High-Temperature Oxidation of hcp-ZrAl2

Abstract

The high-temperature oxidation of ZrAl2 upon exposure to pure O2 at 800–950 °C was studied in terms of the oxidation kinetics and the formation mechanism of the oxide layer. The alloy followed parabolic oxidation kinetics, and the activation energy of oxidation was 239 ± 14 kJ/mol. During the early stages of oxidation below 850 °C, a single-layer oxide formed due to the crystallization of the initially formed amorphous oxide layer. A multilayer oxide structure developed at higher temperatures, due to the slightly higher affinity of oxygen for Zr than for Al and the oxidation-induced compositional changes.