Covers the reaction processes from oxide failure nucleation, through scale growth, as well as the possibilities of alloy design for improved oxidation resistance using a wide range of microscopical techniques.
An understanding of oxidation is essential for the study and development of advanced materials, particularly those which must withstand high temperatures. The 56 papers in this volume examine the behaviour of metals, alloys and ceramics when exposed to different environments and discuss the latest analytical microscopical techniques currently used in materials science.
Corrosion and anti-corrosives by Michael John Bennett
Static oxidation kinetics of Ti14Al21Nb (wt pct) ingot alloy were studied in air over the temperature interval of 649 to 1093 C in a thermogravimetric apparatus. The oxidation products were characterized by x ray diffraction, electron microprobe analysis, energy dispersive x ray analysis, and Auger electron spectroscopy. Cross-sections of the oxidized samples were also examined using light and scanning electron microscopy. The oxidation rate was substantially lower than the conventional alloys of titanium, but the kinetics displayed a complex behavior involving two or more oxidation rates depending on the temperature and duration of exposure. The primary oxide formed was TiO2, but this oxide was doped with Nb. Small amounts of Al2O3 and TiN were also present in the scale. Diffusion of oxygen into the alloy was observed and the diffusivity seemed to be dependent on the microstructure of the metal. A model was presented to explain the oxidation behavior of the alloy in terms of the reduction in the oxygen diffusivity in the oxide caused by the modification of the defect structure of TiO2 by Nb ions. Sankaran, Sankara N. and Clark, Ronald K. and Unnam, Jalaiah and Wiedemann, Karl E. Langley Research Center RTOP 505-43-71-01...