Deformation-induced nonequilibrium grain-boundary phase in submicrocrystalline iron

Mössbauer spectroscopy of Fe-based nanomaterials

“…Also, σ = 217 A·m 2 /kg for both the initial α-Fe and for the milled one. Taking into account the data obtained in this work and in [11,13,14,[17][18][19][20], we conclude that the formation of additional sextet in the Mössbauer spectrum of nanocrystalline iron [1][2][3][4][6][7][8][9][10][11]] is related to an uncontrolled impurity, whereas the formation of the sextet with H = 21 T and the Curie temperature equal to 480 K [7], observed after annealing of the milled iron, is related to the presence of the Fe 3 C carbide.…”

“…According to the results published in Refs. [1][2][3][4][6][7][8][9][10][11], for the MA(16 h) sample, we could expect lower P 0 and higher P 1 values than those shown in Table 2. P k values for the annealed sample are considerably different from those expected for the fully disordered state.…”

“…Thus, no second component [1][2][3][4][6][7][8][9][10][11] with the HFMF of H = 30.5-31.1 T and a wide distribution of HFMFs (Γ 1,6 = 0.4-1.6 mm/s) was found in the Mössbauer spectra of iron powders with a nanocrystalline structure. No second subspectrum with a HFMF of 21 T [7] was found in the Mössbauer spectrum of the milled iron powder subsequently annealed at 773 K ( Fig.…”

“…The estimates show that the volume fraction of the interface regions, provided the grain size is less than 10 nm, can be up to 50%. In a number of papers studying nanocrystalline α-Fe, it has been maintained that the interface regions essentially differ in the structure and fundamental magnetic properties (such as specific saturation magnetization, hyperfine interaction parameters, additional sextet in the α-Fe Mössbauer spectra, Curie temperature) from those in the bulk of the crystal [1][2][3][4][5][6][7][8][9][10]. On the other hand, it has been found [11][12][13][14][15][16] that irrespectively of the technique for producing nanocrystalline α-Fe (gas condensation, mechanical treatment in mills, high-pressure shearing), a possible significant contamination of α-Fe by impurities, contained in the medium, may occur.…”

“…J.Phys. 56 (2006) A E41sub-spectrum with HFMF of 30.5-31.1 T[1][2][3][4][6][7][8][9][10][11] correlates with the volume fraction of the interface regions. However, it is seen from…”