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Space agencies are working on the project of capturing asteroids which contain natural resources valuable for industry. Based on studies of meteorites samples it was determined that the most useful source of raw materials for this purpose could be parent bodies of ordinary chondrites of type H. The identification of the type of ordinary chondrites with the use of a classical method (determination of the Fa/Fs ratio (fayalite versus ferrosilite) by electron microprobe measurements) cannot be performed on the surface of asteroids due to technical reasons. It may, however, be done based on Mössbauer measurements followed by the application of the 4M method. The name of the method – 4M, comes from four words: Meteorites, Mössbauer spectroscopy, Multidimensional discriminant analysis and Mahalanobis distance. Following the success of Mössbauer spectroscopy in the mission on Mars, there are suggestions to use the same method for the investigation of the surface of asteroids. In our experimental study, in which five Mössbauer laboratories took part, we assessed the effectiveness and reliability of the 4M method by comparison of the results obtained by Mössbauer studies of ordinary chondrites of type H, L and LL. Details of the study and problems related to the effectiveness of the 4M method are discussed.

An elemental powder mixture of Fe-50 at.%Al with addition of 30 vol% of B was subjected to mechanical alloying (MA). Phase transformations occurring in the material throughout MA were investigated by Mossbauer spectroscopy. Examination of thermal behaviour of the MA product by differential thermal analysis revealed four exothermic peaks. Structural and phase transformations induced in the MA powders by heating in a calorimeter up to 530, 630, 730 and 1000 °C were investigated by X-ray diffraction and Mossbauer spectroscopy. The powders containing 30% of B in the as-milled state and after heating up to 1000 °C were examined by scanning electron microscopy. Magnetic properties of the MA product before and after heating up to 1000 °C were investigated. It was found that MA of the (Fe-Al)-30 vol%B powders resulted in the formation of a composite structure with boron particles embedded in the predominantly amorphous Fe-Al-B matrix. Additional Mossbauer measurements performed on MA products with a smaller boron content of 5, 10 and 20 vol% evidenced the crucial role of boron addition in promoting the formation of Fe-Al-B amorphous phase by MA process. The structure of the (Fe-Al)-30 vol%B powders after their controlled heating comprised of fine B particles distributed in the two-phase matrix of nanocrystalline (FeAl or AlFe2B2-type) and amorphous phases or in the nanocrystalline matrix (AlFe2B2 + Al13Fe4), depending on the temperature up to which the material was heated. To the best of our knowledge, the nanocrystalline AlFe2B2 phase was obtained for the first time by mechanical alloying followed by heat treatment.

The article presents the results of research on the structural evolution of the composite Fe-Al-based coating deposited by arc spray with initial low participation of in situ intermetallic phases. The arc spraying process was carried out by simultaneously melting two different electrode wires, aluminum and low alloy steel (98.6 wt.% of Fe). The aim of the research was to reach protective coatings with a composite structure consisting of a significant participation of FexAly as intermetallic phases reinforcement. Initially, synthesis of intermetallic phases took place in situ during the spraying process. In the next step, participation of FexAly fraction was increased through the annealing process, with three temperature values, 700 °C, 800 °C, and 900 °C. Phase structure evolution of the Fe-Al arc-sprayed coating, stimulated by annealing, has been described by means of SEM images taken with a QBSD backscattered electron detector and by XRD and conversion electron Mössbauer spectroscopy (CEMS) investigations. Microhardness distribution of the investigated annealed coatings has been presented.

Nanocrystalline Fe80-x-yCoxNiyCu1Nb3Si4B12 alloys were prepared by the annealing of amorphous ribbons. Primary crystallization of the alloys annealed at temperatures of between 500 and 550°C was studied by X-ray diffraction and Mössbauer spectroscopy. Magnetic properties of the alloys were investigated using a hysteresis loop tracer and vibrating sample magnetometer. The annealed ribbons are composed of a two-phase nanostructure consisting of bcc Fe-based grains embedded in an amorphous matrix. Conversion electron Mössbauer spectroscopy (CEMS) measurements reveal a more advanced crystallization process in the surface layers when compared with the volume of the ribbons. The degree of saturation magnetization of the nanocrystalline alloys is of about 1.5 T. The coercive field varies from 1.0 to 6.5 A/m and peaks at an annealing temperature of 525°C. Magnetic softening of the nanocrystalline alloys observed after annealing at 550°C is correlated with a volume fraction of the nanocrystalline bcc phase.

This work was supported by National Science Centre, Poland, through grant no. PW-0415-003., The preliminary results of 57Fe Mössbauer spectroscopy and X-ray diffraction (XRD) of fully metamict samarskite dated at ~1500 Ma, which absorbed α-dose of 6.5 × 1017 α-decay mg-1, are reported after one-hour annealing at 673, 873, 1173 and 1373 K in argon atmosphere. Metamict minerals contain radioactive elements that degrade their crystal structures over geological time. All the Mössbauer spectra obtained can be fitted to two quadrupole doublets assigned to Fe2+ and Fe3+ in octahedral positions. The relative contribution of Fe2+ (Fe2+/Fe) reaches a minimum of 0.10 at 1173 K., NCN

In the present work, we investigated in detail the thermal/crystallization behavior and magnetic properties of materials with Fe84.5-xCoxNb5B8.5P2 (x = 0, 5, 10, 15 and 20 at.%) composition. The amorphous ribbons were manufactured on a semi-industrial scale by the melt-spinning technique. The subsequent nanocrystallization processes were carried out under different conditions (with/without magnetic field). The comprehensive studies have been carried out using differential scanning calorimetry, X-ray diffractometry, transmission electron microscopy, hysteresis loop analyses, vibrating sample magnetometry and Mössbauer spectroscopy. Moreover, the frequency (up to 300 kHz) dependence of power losses and permeability at a magnetic induction up to 0.9 T was investigated. On the basis of some of the results obtained, we calculated the values of the activation energies and the induced magnetic anisotropies. The X-ray diffraction results confirm the surface crystallization effect previously observed for phosphorous-containing alloys. The in situ microscopic observations of crystallization describe this process in detail in accordance with the calorimetry results. Furthermore, the effect of Co content on the phase composition and the influence of annealing in an external magnetic field on magnetic properties, including the orientation of the magnetic spins, have been studied using various magnetic techniques. Finally, nanocrystalline Fe64.5Co20Nb5B8.5P2 cores were prepared after transverse thermo-magnetic heat treatment and installed in industrially available portable heating equipment.

The paper presents the results of research on the production by means of arc spraying of composite coatings from the Fe-Al system with participation of in-situ intermetallic phases. The arc spraying process was carried out by simultaneously melting two different electrode wires, aluminum and steel. The aim of the research is to create protective coatings with a composite structure with a significant participation of FexAly as an intermetallic phases reinforcement. The synthesis of intermetallic phases takes place during the (in-situ) spraying process. Currently most coatings involving intermetallic phases are manufactured by different thermal spraying methods using coating materials in the form of prefabricated powders containing intermetallic phases. The obtained results showed the local occurrence of intermetallic phases from the Fe-Al system, and the dominant components of the structure have two phases, aluminum solid solutions in iron and iron in aluminum. The participation of intermetallic phases in the coating is relatively low, but its effect on the properties of the coating material is significant.

The aim of the present work is to study the magnetic properties of ZrO2(Fe) nanocrystals prepared by the wet chemistry method. The microwave assisted hydrothermal synthesis was used. The detailed structural characterization was performed by means of X-ray diffraction and TEM studies. 57 Fe Mossbauer spectra were recorded at room temperature for all samples. The isomer shift and quadrupole splitting indicate the presence of Fe 3+ ions. The systematic measurements of AC magnetic susceptibility up to 350 K and magnetization as a function of magnetic field (up to 9 T) and temperature were performed. Depending on the nominal concentration of magnetic dopant different types of magnetic behavior, were observed. 2015 Elsevier B.V. All rights reserved.

We report the results of 57Fe Mossbauer spectroscopy, gamma-ray spectrometry and X-ray diffraction of two fully metamict samarskites and two partially metamict gadolinites. The absorbed α-dose for these minerals are found to range from 3.6 × 1015 α-decay/mg for one of the gadolinite samples to 7.7 × 1017 α-decay/mg for one of the samarskite samples. The Mossbauer spectra of samarskites and gadolinites show increasing line widths of the Fe2 + doublets with absorbed α-dose. We also observe that the increase in average quadrupole splitting of the Fe2 + cmponents correlates better with absorbed α-dose from 232Th than with total α-dose.

We report the preliminary results of 57Fe Mossbauer spectroscopy, gamma-ray spectrometry and X-ray diffraction (XRD) analysis of five complex metamict minerals: brannerite, cerite, columbite, perrierite and samarskite The absorbed α-dose for these minerals vary widely, ranging from 1.3 × 1015 α-decay/mg (cerite) to as high as 2.0 × 1018 α-decay/mg (brannerite). The Mossbauer spectra show decreasing isomer shift values for Fe2 + components with absorbed α-dose. One unexpected result of these spectra is a nearly complete crystallinity of the columbite sample despite its high absorbed α-dose of 1.9 × 1016 α-decay/mg.

Iron–aluminum alloy of Fe–50% Al composition was prepared by mechanical alloying (MA) of the elemental powders. Thermal behaviour of the milled powders was examined by differential scanning calorimetry (DSC). The phase transformations and structural changes occurring in the studied material during mechanical alloying and during subsequent heating in a calorimeter were investigated by X-ray diffraction (XRD) and Mossbauer spectroscopy. The final product of the MA process was the nanocrystalline Fe(Al) solid solution with a mean crystallite size of 15 nm. It was found that the Fe(Al) solid solution was formed not by the gradual solution of Al into bcc Fe but by the rapid formation of small zones of Fe(Al) with the ultimate composition, coexisting with the remaining Al and Fe phases. With the increase of milling time all Al atoms became dissolved in the bcc Fe. The disordered Fe(Al) solid solution transformed into the ordered FeAl intermetallic compound upon heating of the milling product in the calorimeter. After the heating the material remained nanocrystalline. The Mossbauer study of the heated samples showed two types of Fe atomic configurations: the dominating one related to the ordered FeAl phase and the other one related to iron atoms located in less ordered regions.

The crystallization process of the amorphous Fe 81 Zr 7 B 12 alloy induced by short time annealing at 600°C is studied by γ-transmission and conversion electron Mossbauer spectroscopy (CEMS). Structural transformations as a function of annealing time (15-120 s) are compared with those induced by 1 hour anneals. CEMS measurements reveal considerably stronger crystallization at the surfaces of the ribbon than in the bulk. Unconventional rf-Mossbauer technique is employed to study changes in magnetic properties due to annealing of the Fe 81 Zr 7 B 12 alloy. The radio-frequency (rf) collapse effect allows the estimation of magnetic anisotropy fields in the amorphous and nanocrystalline phases. The decrease of magnetostriction due to the formation of the nanocrystalline phase is observed by rf sidebands effect.