Oxidation Behavior of a Fine-grained Chromium-containing Ni3 Al Alloy Prepared by Powder Metallurgy

Abstract

The oxidation behavior of a fine-grained Cr-containing Ni 3 Al based alloy was evaluated between 500 and 1000 • C for exposures up to 2000 h. The alloy showed low oxidation rates over the entire temperature interval due to the formation of a thin protective alumina layer. The growth of this healing layer was promoted by both the fine microstructure of the alloy and the chromium additions. Rapid formation of the alumina layer was observed even at temperatures as low as 500 • C. During the whole exposure at temperatures below 800 • C the alumina layer remained adherent. However, at 800 and 900 • C some spalling was observed. Usually, spalling took place at the core of the alumina layer but not at the oxide/metal interface.