Structural and Magnetic Relaxation of Fe61Co10Y8Mo1B20 Bulk Amorphous Alloy Obtained Using Two Methods

Bulk amorphous Fe61Co10Y8Mo1B20 alloys in the form of plates have been prepared using two methods: suction casting and injection casting. The structure of the as cast samples have been studied using Mossbauer spectroscopy. The obtained Mossbauer spectra are typical for materials of amorphous structure. In the hyperfine field distributions obtained from the Mossbauer spectra analysis, there are variations between the probability of occurrence of magnetic atoms around central atom. Then, magnetic susceptibility disaccommodation has been measured for the tested samples. These measurements indicate that the structural relaxation in the studied samples occur at the elementary level. Injection casting method for the tested alloy determines, in the material volume, the formation of more point relaxators in the form of free volume.

The Influence of Heat Treatment on the Shape of 57Fe Hyperfine Field Induction Distribution in Massive Amorphous Fe61Co10Y8X1B20 (where X = Mo, W)

The paper presents the results of Mossbauer research for massive amorphous alloys Fe61Co10Y8Mo1B20 and Fe61Co10Y8W1B20 manufactured using the method of suction of a liquid alloy into a copper water-cooled mold and subjected to thermal treatment at a temperature of 700K / 60 min and 770K / 210 min. The treatment was carried out below the crystallization temperature and it did not lead to the creation in the volume of alloys of crystalline systems showing long-range order of atoms. M�ssbauer research was performed for low energy milled plates in transmission geometry. Then, numerical analysis of these spectra was performed and the corresponding hyperfine field distributions were obtained 57Fe. It has been shown that isothermal annealing has a big influence on the shape of the hyperfine field distribution. As a result of thermal processing, diffusion of the components took place, which caused the occurrence of diverse environments of iron atoms around the central atom. In the volume of all specimens, there was a lack of topological order in the arrangement of atoms.

Mossbauer Studies of Rapid Cooled Amorphous Iron Alloys in as Cast State

The study investigated the effect of a small alloy addition (1 atomic %) in alloys Fe61Co10Y8Nb1B20, b - Fe61Co10Y8Zr1B20, c - Fe61Co10Y8W1B20, d - Fe61Co10Y8Mo1B20 on the shape of the Mossbauer spectrum and on the distributions of hyperfine field induction on 57Fe obtained from their numerical analysis. The line factor A [2.5] was also determined in the Zemman�s sextet, which is an indirect measure of ordering for the texture of the spins occurring in the volume of alloys. Based on the analysis of the results, it was found that the Mossbauer spectras are typical of amorphous alloys and the hyperfine field distributions are bimodal.

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 confirmed by modifications of the shapes of hyperfine 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 and magnetization studies of mechanically milled nanocrystalline Fe1–xAlx alloys

Changes in the magnetic behavior of Fe1–xAlx (x = 0.3, 0.4, 0.5, 0.6) powders during mechanical alloying have been studied. The ball milling process leads to formation of solid state reaction assisted by severe plastic deformation because of which crystallite size is reduced and as a result of which interesting magnetic properties are developed. The evolution of magnetic order in high-energy ball-milled Fe–Al solid solution is investigated using 57Fe Mössbauer spectroscopy and vibrating sample magnetometer. Mössbauer spectra and the hyperfine field distributions of all the samples show the presence of both magnetic and paramagnetic components in the samples. The corresponding bulk magnetization studies also show that the Al rich samples are also ferromagnetic, which can be attributed to the presence of disordered Fe-rich phases due to the non-equilibrium process of alloying. In Fe-rich samples, the formation of an off stoichiometric Fe3Al phase is favored while in the case of Al-rich samples both Al-rich phases and clustering of Fe and Al atoms are present. The systematic variation in the magnetic properties has been qualitatively correlated with the evolution of microstructure, reduction in grain size (obtained using transmission electron microscopy) and enhanced intergranular exchange coupling.

Magnetic and structural properties of Sc(Fe1−xSix)2 Laves phases studied by Mössbauer spectroscopy and neutron diffraction

The aim of the presented paper is to study an influence of replacement of Fe atoms by Si atoms in quasibinary Sc(Fe1−xSix)2 Laves phases on their structural and magnetic properties. Powder X-ray diffraction (XRD) and neutron diffraction (ND) measurements carried out at different temperatures from 4.3 K up to about 700 K revealed that samples were single phase with cubic C15 structure for Si concentration x from 0.05 to 0.20 and hexagonal C14 structure for higher concentration. The results of 57Fe Mössbauer measurements showed that the Sc(Fe1−xSix)2 compounds with x ≤ 0.30 are ferrimagnetic at 4.3 K. At temperature 80 K in the samples with x = 0.20 and 0.30, a magnetic cluster spin-glass state has been observed, as ferrimagnetic long-range order disappears. Such picture was supported by the results of ND measurements carried out at 8 K, which confirmed the lack of long-range order for x above 0.10 and an occurrence of hyperfine field distributions in the corresponding Mössbauer spectra. At room temperature, samples with x ≥ 0.20 became paramagnetic. A substitution of Si atoms for Fe ones leads to a decreasing of mean values of hyperfine magnetic fields in samples under investigation. From the neutron diffraction pattern analysis of Sc(Fe0.90Si0.10)2Fe magnetic moment was determined as to be equal to 1.5 μB at 8 K. Combining this result with a value of hyperfine magnetic field on 57Fe probes, the hyperfine coupling constant A in Sc(Fe0.90Cu0.10)2 phases is estimated at about 11.6 T/μB at 8 K.

Effect of heat treatment on the shape of the hyperfine field induction distributions and magnetic properties of amorphous soft magnetic Fe62Co10Y8B20 alloy

Thermal treatment, undertaken at just below the crystallization temperature, has led to nanocrystallization and has had a significant impact on the shape of the hyperfine field induction distributions of Fe62Co10Y8B20 alloy and on its soft magnetic properties. In the amorphous ferromagnetic alloys, it is possible to indirectly determine the effect of the structure stresses, resulting from the presence of structural defects, on the soft magnetic properties of these materials. It has been found that a change in the parameters associated with the presence of structural defects affects the shape of the hyperfine field distributions of 57Fe.

Mössbauer and Magnetization Measurements of Al3Mn(Pd,Fe) Compounds

Magnetic and 57Fe Mössbauer measurements are reported on Taylor-phase compounds T-Al3Mn(Pd,Fe), which are complex metallic alloys containing 156 atoms in the unit cell. These investigations are extended to Al71Mn19Fe10 which crystallize as decagonal quasicrystal. Common for all samples spin glass behavior is present at low temperatures with freezing temperatures Tf increasing (decreasing) with Fe (Pd) content. Below Tf rejuvenation and memory effects are observed in aging investigations. Above Tf the 57Fe Mössbauer spectra were analysed by a superposition of two subspectra with intensity ratio around 75:25, which might be allocated to Fe substituted on Mn sites surrounded either by Al and Mn or completely by Al in the nearest neighborhood. Below Tf broad hyperfine field distributions are present.