The Microstructure of Oxidized Consolidated Nanocrystalline NiAl

Abstract

<jats:p>The intermetallic, stoichiometric compound NiAl is a candidate for aggressive environments such as those encountered in aircraft engines due to its excellent oxidation resistance and high melting point. However, NiAl is limited in application by its insufficient ambient temperature ductility. This may potentially be overcome via synthesis of NiAl with a nanocrystalline microstructure. Since microstructure can also affect oxidation resistance [1], the focus of this investigation is to examine the oxidation characteristics of nanocrystalline NiAl.</jats:p><jats:p>Nanophased NiAl specimens were prepared by mechanical alloying followed by shock wave consolidation, which yielded consolidated material with an average grain size of 11 ±8 nm [2]. Thermogravimetric analysis (TGA) of nanosized NiAl was used to characterize the material's oxidation resistance, and performed for three different times (0.5 h, 5 h, 48 h) in compressed air at 1373 K. It was found that the thickness of the scale increased with increasing oxidation time, in accordance with parabolic oxidation kinetics.</jats:p>