High temperature oxidation behavior of NiTiNb intermetallic alloys

An intensive experimental study was made of the cyclic oxidation behaviors of NiTiNb alloys (0-7 at.% Nb) with single B2 phase at elevated temperatures of 600 degrees C and 800 degrees C in air. The micro-structural evolution of the multi-layers oxide on the alloys was investigated and the effect of Nb on the oxidation characteristics of NiTiNb alloys was evaluated. It is shown that the addition of Nb can remarkably improve the oxidation resistance of NiTiNb alloys at high temperature. Further, the corresponding mechanism for the improvement of the oxidation resistance by Nb addition has been probed. Nb-rich oxide layer formed can effectively impede interdiffusion of oxygen and metallic cations during oxidation process, leading to a remarkable improvement of oxidation resistance of NiTiNb alloys at high temperature. (C)2007 Elsevier Ltd. All rights reserved.