Abstract
Austenitic (fcc) Fe-Mn-Al alloys were nitrided in the temperature range 723 to 973 K by a glow discharge method using H2-N2 gas mixtures, and the microstructures and compositions of the nitrided layers were investigated in detail. A thin surface layer and a thick nitrogen-diffused layer (internal nitrided layer) were produced; the former consisted of both manganese nitrides and a ferritic (bec) phase, while the internal nitrided layer had an austenitic structure with the incorporated excess nitrogen atoms. X-ray photoelectron spectra revealed that the incorporated nitrogen atoms have a strong interaction with aluminium lattice atoms. By nitriding, hardness values of the Fe-Mn-Al alloys were increased fromH v = 350 to ca. 1000, and the corrosion resistance to sulphuric acid solution was enhanced by a factor of 30. These improvements are associated with a uniform distribution of the incorporated nitrogen and also with the presence of nitride-like interactions between the nitrogen and aluminium atoms.
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Sato, K., Takahashi, K., Inoue, Y. et al. Surface layers produced by ion nitriding of austenitic Fe-Mn-Al alloys and the effects on hardness and corrosion resistance. J Mater Sci 23, 4445–4449 (1988). https://doi.org/10.1007/BF00551943
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DOI: https://doi.org/10.1007/BF00551943