Akademik Veri Yönetim Sistemi
CORROSION SCIENCE, cilt.37, sa.3, ss.413-428, 1995 (SCI-Expanded)
The effect of exposure to nitrogen-containing environments on two ferritic ODS alloys viz. MA 956 and ODM 751 has been investigated for temperatures ranging between 1200 and 1300 degrees C. A pilot study at 1300 degrees C in oxygen-free nitrogen revealed catastrophic modifications to the entire microstructure of MA 956 with evidence of formation of coarse AlN particles. In order to probe into the exact mechanism of nitridation in these alloys, exposure tests in a flowing mixture of 2% oxygen in nitrogen were performed al 1200 degrees C. In addition to internal nitridation, internal oxidation was also seen. To reduce the kinetics even further, and to investigate the effect of both the Al content and the sample thickness on the nitridation behaviour of these alloys, further tests were performed in stagnant air using samples with varying thicknesses. It was found that when the overall Al content in the matrix reached a critical level (between 1.5-1.7 wt%), breakaway oxidation occurred which accelerated the internal nitridation behaviour.