Comparison of dispersion hardening by coherent and incoherent nitrides in nitriding of alloys based on iron, nickel, and cobalt

Abstract

1. A comparison of the efficiency of dispersion hardening of Ni-, Co-, and Fe-matrices has shown that steels are reinforced more strongly by coherent particles (the Mott-Nabarro model), which requires the lowes volume fraction of nitrides and the lowest concentration of the nitride-forming element in the alloy. In actual Ni- and Co-base alloys the highest hardening effect can be obtained due to incoherent particles too (the Orowan model) given that the nitride particles have optimum geometrical characteristics (the size and the distance between the particles). 2. The results of measurements of the microhardness of nitrided alloys agree well with the calculated data, which makes it possible to use models, in particular, for comparing the level of the hardening of individual alloys by various nitrides or segregations of different sizes. 3. The results of the evaluation of dispersion hardening by nitrides can be used for choosing nitriding regimes with the aim of providing maximum hardening