The oxidation resistance of submicron-grained NiAl-Al2O3 composite fabricated by pulse current auxiliary sintering

Dense and submicron-grained NiAl-Al2O3 composite was fabricated by mechanical alloying and subsequent pulse current auxiliary sintering (PCAS). The isothermal and cyclic oxidations were carried out at 900-1100 degrees C with intervals of 100 degrees C in order to investigate its oxidation resistance. The results indicate that submicron-grained NiAl-Al2O3 exhibits excellent oxidation resistance. A dense and continuous alpha-Al2O3 scale is formed after oxidation. The grain refinement is found to be beneficial for the improvement of oxidation resistance, because it can promote the selective oxidation of Al, provide more nucleation points and improve the adhesion of the alpha-Al2O3 scale. Moreover, a model of leading edge was fabricated by sinter-forging technology with short process in the PCAS furnace to evaluate the practical application of submicron-grained NiAl-Al2O3. Its oxidation resistance was tested by cyclic oxidation at 1100 degrees C. The result reveals that the NiAl-Al2O3 leading edge exhibits favorable oxidation resistance, which is consistent with the results of the test specimens. (C) 2012 Published by Elsevier Ltd.