Alloying element nitride stability in iron-based alloys; denitriding of nitrided Fe–V alloys

Abstract

Recognising the various types of absorbed nitrogen in nitrided iron-based alloys and the lack of accuracy in local composition analysis of the individual nano-sized nitride precipitates (e.g. by atom probe tomography), precise determination of the nitride composition requires so-called denitriding treatments. This study proposes two routes to determine the nanonitride stoichiometry, which are demonstrated by experimental analysis of the denitriding behaviour in hydrogen gas of nitrided, model Fe–V alloys. The minimal nitrogen activity to stabilise the alloying element nitrides MeN in Fe–Me–N alloys is calculated. A strategy is offered to stabilise the alloying element nitrides and to determine the nitrogen content strongly bonded in the nitrides. © 2016 Institute of Materials, Minerals and Mining.