Factors affecting the nitridation behavior of Fe-base, Ni-base, and Co-base alloys in pure nitrogen

The behavior of alloys in nitrogen at high temperature is relevant to many industrial applications. Embrittlement due to internal nitride formation is the principal problem encountered in service. In this study, the nitridation resistance of a series of alloys in pure nitrogen at 1093 O C was investigated. For Fe-base, Ni-base, and Co-base alloys the amount of nitrogen absorbed and the nature and morphology of the nitrides formed was studied. It was found that alloys rich in nickel were most resistant to nitridation. Most of the alloys formed internal chromium nitrides. The Al-containing alloys with about 4.5 wt% Al, formed a surface scale of AlN and was very resistant to nitridation attack.