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

A novel approach to quantify nitrogen distribution in nanocrystalline-amorphous alloys

“…2(a) and Table 1, revealing a combination of nanocrystalline (ferrite (␣), austenite (␥)) and amorphous phases in the materials. Amorphization can be explained via high energy given to the powders during milling and the effect of nitrogen on the increase in the atomic size mismatch and heat of mixing of the alloys [4][5][6][7][8][9]. The details of the calculations of the amorphous quantitative analysis by the Rietveld method have been illustrated in Ref.…”

“…[4,9]. The nitrogen amount of the as-milled powders was determined by a LECO gas analyzer (Corp., St. Joseph, MI).…”

“…time increases from 24 h to 168 h. In the case of milling under the nitrogen atmosphere, nitrogen adheres on virgin surfaces created during MA, dissociates, and consequently penetrates into the powders. Since the amount of structural defects generated by severe plastic deformation during milling is significantly high and since the mismatch strain of nitrogen atoms is reduced in the defects, considerable amounts of nitrogen atoms are infused to the powders, leading to the nitrogen supersaturation [1][2][3][4][5][6][7][8][9][10].…”

“…It has been reported that in Fe-1.36N [11] and Fe-4.1N [12] alloys prepared by MA, 25 and 50 percent of nitrogen is entrapped into the crystal interstitial sites, respectively. On the other hand, only 4 percent of total nitrogen is distributed among crystal interstitial sites of mechanically alloyed Fe-18Cr-8Mn-2.5N stainless steel having a nanocrystalline-amorphous structure [9]. In these studies, the nitrogen supersaturation has qualitatively been attributed to preferential sites at dislocation elastic stress fields and nanograin boundaries.…”

“…The generation of a high density of defects during MA increases the nitrogen solubility markedly. In the recent years, noticeable researches on MA of stainless steels under nitrogen have been reported [1][2][3][4][5][6][7][8][9][10]. It has been found that in Fe-Cr-Mn-N stainless steels processed by MA, the considerable content of an amorphous phase exists [4][5][6][7][8][9][10].…”