Nitrogen addition to iron powder by mechanical alloying

Crystal interstitial sites contribution to nitrogen supersaturation in mechanically alloyed Fe–Cr–Mn–N alloys

“…Since the mismatch strain of solute nitrogen is reduced in the defects, a high proportion of nitrogen atoms are diffused down to the defects. Mossbauer studies of high-nitrogen iron powders prepared by MA have signified that a considerable amount of infused nitrogen accumulates at grain boundaries [24,25].…”

“…Moreover, Petrov et al [21] have reported that nitrogen atoms have no detectable affinity to grain boundaries of highalloyed austenitic steels. The nitrogen distribution in Fe-based alloys synthesized by MA under a nitrogen atmosphere has been tacitly analyzed [11,13,[22][23][24]. Most of them have attributed the nitrogen supersaturation to preferential sites at dislocation elastic stress fields and nanograin boundaries developed during MA.…”

“…Most of them have attributed the nitrogen supersaturation to preferential sites at dislocation elastic stress fields and nanograin boundaries developed during MA. Typically, Rawers et al [24,25] have shown that in Fe-4.1N and Fe-1.36N alloys prepared by MA, 50% and 25% of nitrogen are entrapped into the crystal interstitial sites, respectively. To our knowledge, no systematic work has been reported on the contribution of the crystal interstitial sites to the nitrogen supersaturation of stainless steels.…”

Microstructural, thermal and magnetic properties of amorphous/nanocrystalline FeCrMnN alloys prepared by mechanical alloying and subsequent heat treatment

“…Based on the energy of the milling process and the thermodynamic properties of the constituent elements, the alloy can be rendered amorphous by this processing [11]. Nevertheless, the MA process has normally been performed under an inert gas atmosphere like argon; the processing under a reactive gas atmosphere, such as nitrogen has been employed to produce an amorphous phase [12][13][14][15][16] and nanocrystalline compounds [17][18][19][20][21] through the solid-gas reaction.…”

Ball milling induced interstitial atoms redistributions revealed by Mössbauer effect in Fe based alloys

“…Only very sophisticated deconvolutions of carefully obtained diffractograms are likely to avoid ambiguous interpretations. In the case of FeN x this deconvolution achieved by Aufrecht et al [6] has proven that for x ≤ 0.14 the martensitic-like tetragonal structure which had be proposed [9] does not satisfy all the experimental diffraction data and that the α superferritic BCC suggested by Mössbauer spectroscopy [10] and electron diffraction is more realistic [11]. Arguments in favour of α -like structure were also provided by 200 • C ageing of the BM products which in contrast with similar thermal treatment of as-quenched α martensite refused any evidence of α Fe 16 N 2 ordering [12].…”