Depth-Selective Study of Surface Crystallization in NANOPERM-Type Alloys

Evolution of structure and magnetic order is studied in the $\text{}^{57}Fe_{81}Mo_{8}Cu_{1}B_{10}$ alloy by conversion electron and conversion X-ray $\text{}^{57}Fe$ Mössbauer spectrometry. Surface features exhibit differences at both sides of ribbon-shaped samples with respect to the screening depth. In the as-quenched state, traces of magnetite (in addition to bcc-Fe) are revealed only at the wheel side of the ribbon to the depth of about 200 nm. It is present also after annealing up to 510 °C, then it disappears. In deeper regions (down to 1 μm), magnetite is less abundant. At the air side, only bcc-Fe is detected, though the progress of crystallization is more pronounced here than at the wheel side. Vibration properties of the bulk of amorphous and nanocrystalline samples are obtained from experiments of nuclear inelastic scattering of synchrotron radiation using partial densities of phonon states

Identification of Magnetic Phases in LC200N Steel by Backscattering Mössbauer Spectrometry

In this paper we identified iron phases in three different samples of highly corrosion-resistant steel LC200N using the Mössbauer spectrometry which is particularly suited method for this purpose. Special emphasis is put upon magnetically active crystalline phases. The samples had different thermal history: (1) hardened, (2) hardened with consequent rapid quenching in liquid nitrogen, (3) non-hardened and prepared in a disc form with two sides ("as cut" and polished). Both ferritic magnetic phases and non-magnetic austenite phase were found in these samples. Relative content ratios between these phases were determined for each type of the samples and their respective sides. Higher amount of magnetic phases was found in non-hardened sample and on polished sides of all samples in general. The elemental characterization was accomplished by neutron activation analysis

Microstructure and magnetic properties of amorphous Fe51Co12Si16B8Mo5P8 alloy

Microstructure and thermomagnetic characteristics of the amorphous Fe51Co12Si16B8Mo5P8 alloy in the as-quenched state and after 1 h of annealing at 573 K and 773 K are studied. The structural investigations performed by Mössbauer spectroscopy and X-ray diffractometry confirmed the amorphous structure of the analysed materials. An increase in the annealing temperature up to 773 K does not lead to crystallization of the amorphous alloy. Only structural rearrangement that causes changes in the topological short-range order and annealing out of free volume is observed. This behaviour was confi rmed by modifications of the shapes of hyperfi ne field distributions derived from the corresponding Mössbauer spectra of the investigated alloys. The Curie temperatures of the as-quenched and annealed Fe51Co12Si16B8Mo5P8 alloy at 573 and 773 K are 400, 405 and 421 K, respectively

Mössbauer Spectrometry Study of Biological Tissues

Magnetic microstructure of iron contained in selected biological tissues is characterized and mutually compared. We have studied three types of biological samples prepared from human brain, human and horse spleen. Original samples were lyophilized (dried in a vacuum) thus providing powder forms. As a principal method of study, ⁵⁷Fe Mössbauer spectrometry in transmission mode was used. The Mössbauer spectrometry experiments were performed at room ( ≈300 K) and at liquid helium (4.2 K) temperature. At room temperature Mössbauer spectra show doublet-like features. Such behaviour indicates possible presence of nanoparticles with fluctuating magnetic moments that acquire arbitrary positions. On the other hand, low temperature Mössbauer spectrometry measurements demonstrate significant contribution of sextets that confirmed occurrence of blocked magnetic moments of iron-containing particles. Different relative contributions of magnetic components in the low temperature spectra for the three inspected biological tissues suggest differences in the blocking temperatures of the magnetic nanoparticles present in them

Magnetocaloric Properties of Fe₇₅Mo₈Cu₁B₁₆ and Fe₈₁Mo₈Cu₁B₁₀ Metallic Glasses

Microstructure and thermomagnetic properties for the Fe₇₅Mo₈Cu₁B₁₆ and Fe₈₁Mo₈Cu₁B₁₀ metallic glasses in the as-quenched state and after heat treatment at 643 K and 723 K are studied. The inverse change of the Curie point was observed for Fe₇₅Mo₈Cu₁B₁₆ metallic glass after annealing below the onset of crystallization. It is attributed to structural relaxation of the amorphous phase. The maximum of magnetic entropy change calculated for magnetic field of 1.0 T occurs for the Fe₇₅Mo₈Cu₁B₁₆ alloy annealed at 643 K at temperature close to the Curie point and equals 0.74 J kg¯¹ K¯¹