Mossbauer study on local atomic structure in Fe80-xNbxB20 (x = 4, 6) metallic glasses

Fe-based amorphous alloys were prepared by the melt-spinning technique and characterized by X-ray diffraction and transmission Mössbauer spectroscopy. The studies were performed on Fe76Nb4B20 and Fe74Nb6B20 metallic glasses in the form of ribbons. The Mössbauer spectroscopy allows to study the local environments of the Fe atoms in the glassy state, showing the changes in the amorphous structure due to the changing of Nb addition. The obtained Mössbauer spectra of ferromagnetic metallic glasses present broad lines resulting from the distribution of nonequivalent iron sites and of interatomic distances. Variation of Nb content in the alloys affects the disorder in as-cast state and also influences on the average radius of the first coordination shell and the number of nearest neighbor Fe atoms

Structural study and crystallization behaviour of Fe62-xCoxNb8B30 metallic glasses (x = 0, 20)

The paper presents the structural analysis of Fe62xCoxNb8B30 metallic glasses (x = 0; 20) in as-cast and after crystallization state. The studies were performed on metallic glasses of ribbon form with thickness of 0.05 and 0.06 mm. The structure analysis of the samples in as-cast state and phase analysis of studied alloys after annealing was carried out by the X-ray diffraction methods. Moreover, the Mössbauer spectroscopy was also used to investigate the local structure for examined alloys. The soft magnetic properties examination covered the initial magnetic permeability. The after-effects of magnetic permeability were also conducted

Structure studies of Fe-based metallic glasses by Mossbauer spectroscopy method

Purpose: The paper presents a structure characterization of selected Fe-based metallic glass in as-cast state.Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 metallic glass in form of ribbons. The amorphous structure of tested samples was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. Mössbauer spectroscopy method was applied to comparison of structure in studied amorphous samples with different thickness (cooling rates).Findings: The XRD, TEM and Mössbauer spectroscopy investigations revealed that the studied alloy in as-cast state was amorphous. Comparison of diffraction patterns of studied samples with different thickness showed the slightly narrowing of diffraction lines. The TEM observations also revealed a changing of image contrast of glassy ribbons with increase of sample thickness. The Mössbauer spectra presented broadened six line patterns characteristic to the structural disorder of amorphous ferromagnetic materials. The hyperfine magnetic field distributions for studied sample thickness indicated the existence components corresponding to the regions with different iron concentration (an iron-rich and an iron-poor surroundings).Practical implications: The Mössbauer spectroscopy is very useful method in studying the structural environment of Fe atoms on a nearest-neighbor length scale allowing the analysis of iron-containing phases.Originality/value: The obtained examination results confirm the utility of investigation methods in analysis of microstructure in function of sample thickness

Corrosion properties of electrodeposited Cu/Co multilayers

The paper presents the results of corrosion resistance of Cu/Co multilayer systems fabricated by using the electrolytic method. The systems obtained were composed of layers differing in number and thickness, which was determined by observing the cross-sections of the samples using scanning electron microscopy (SEM). The measurements of multilayer system corrosion properties carried out in 3,5 % NaCl solution showed different corrosion resistance depending on system thickness. The microscopic observations revealed the effect of the aggressive environment on the Cu/Co multilayer systems manufactured, adopting various forms of corrosion degradation

Microstructure investigations of Co-Si-B alloy after milling and annealing

Purpose: The work presents the microstructure characterization of Co77Si11,5B11,5 metallic glass after high-energy ball milling and heat treatment processes. Design/methodology/approach: The studies were performed on ribbon prepared by melt spinning and this ground in high-energy vibratory ball mill. The tested ribbon and obtained powders were also annealed in specified heat treatment conditions. The morphology of the powder particles of milled ribbon was analyzed by using the confocal laser scanning microscope. The methods of X-ray diffraction were used for the qualitative phase analysis. The parameters of the individual diffraction line profiles were determined by PRO-FIT Toraya procedure. The average crystallite sizes and lattice distortions for Co phase were estimated using Williamson-Hall method. Findings: The studied Co77Si11.5B11.5 metallic glass in annealed state contains hexagonal Co crystalline phases emerged in amorphous matrix. The crystallite size of Co phase in as-cast sample lies in nanoscale. After annealing process the crystallite size increases to 72 nm and diminishes to 46 nm in the powder sample after 30 hours of milling. The milling causes decrease of the crystallite size and increase of lattice distortions of crystalline phase. The powder particles after 30 hours of milling are of spherical shape. Practical implications: The powder particles obtained after milling process of Co-based metallic glass could be suitable components in production of ferromagnetic nanocomposites. Originality/value: The obtained results confirm the utility of applied investigation methods in the microstructure analysis of powder materials with nanocrystalline phases. Keywords: X-ray phase analysis; Toraya procedure; High

Microstructure of composite material with powders of barium ferrite

Purpose: The aim of the present work is the microstructure characterization of commercial powder BaFe12O19 (as-prepared) and composite material with BaFe12O19 powders and polymer matrix, using XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy) methods. Design/methodology/approach: The morphology of barium ferrite powders and a fracture surface of the examined composite material was realized by using the scanning electron microscope. The methods of Xray diffraction were used for the qualitative phase analysis. The parameters of diffraction line profiles were determined by PRO-FIT Toraya procedure. Findings: The X-ray diffraction analysis permitted on identification the BaFe12O19 and Fe2O3 phases in an examined material. Basing on Toraya method is determination of: lattice parameters, crystallite size (D) and the lattice distortion (). Distribution of powders of barium ferrite in polymer matrix is irregular and powder particles have irregular shapes and dimensions. Research limitations/implications: For future research the X-ray analysis should be performed by the Rietveld method, which allows to characterization the microstructure of tested material and verification of its qualitative phase composition. Originality/value: The applied Toraya method of structure analysis appeared to be very useful in the microstructure analysis

The influence of manufacturing conditions on microstructure and magnetic properties of BaFe12O19 powders

The aim of the paper was a trial of using mechanical alloying process of mixture iron oxide and barium carbonate to produce BaFe12O 19 powders. The milling process was carried out in a vibratory mill for 10, 20 and 30 hours. The size distributions of powder particles showed that the size of tested particles increases with the increase of milling time indicating the agglomeration process of particles. The milling process of Fe2O3 and BaCO3 mixture for studied milling times causes decrease of the crystallite size of involved phases and leads to increase of Fe2O3 phase content and decrease of BaCO 3 one. The milling process did not lead to formation of BaFe 12O19 phase, thus it probably causes setting of Fe 2O3 on surface layer of BaCO3 powder particles. The XRD investigations of Fe2O3 and BaCO3 mixture milled for 10, 20 and 30 hours and annealed at 1000°C for 1 hour enabled the identification of hard magnetic BaFe12O19 phase. For applied magnetic field of 800 kA/m, the coercive force is equal to 343 kA/m, 358 kA/m and 366 kA/m whereas the remanence is equal to 0.118 T, 0.109 T and 0.127 T for the samples after milling for 10, 20 and 30 hours, respectively

Mossbauer investigations of amorphous Fe(80-x) B20Nbx (x=0,4,6,10) alloys

Purpose: The paper presents a structural and magnetic characterization of selected Fe-based metallic glasses in as-cast state. Design/methodology/approach: The studies were performed on Fe(80-x)B20Nbx metallic glasses in form of ribbons with Nb addition of 0, 4, 6, 10 at.%. The amorphous structure of tested samples was examined by X-ray diffraction (XRD) and Mössbauer spectroscopy methods. The Mössbauer spectroscopy was also applied to comparison of structure in studied amorphous samples with different chemical composition. The thermal properties associated with solidus temperature of master alloys were measured using the differential thermal analysis (DTA). The soft magnetic properties examination of tested materials contained relative magnetic permeability. Findings: The XRD and Mössbauer spectroscopy investigations revealed that the studied alloys in as-cast state were amorphous. The solidus temperature assumed as the onset temperature of the melting peak on the DTA curve reached a value of 1405, 1394, 1392 and 1389 K for Fe80B20, Fe76B20Nb4, Fe74B20Nb6 and Fe70B20Nb10 alloy, adequately. The Mössbauer spectra presented broadened six line patterns characteristic to the structural disorder of amorphous ferromagnetic materials. The changing of the average hyperfine magnetic field with niobium addition is connected with structural changing. A high concentration of Nb atoms with high atomic radius can acting as diffusion barrier what lead to formation of regions rich in iron or boron atoms. The niobium addition in Fe(80-x)B20Nbx alloy improves soft magnetic properties in as-cast state. Practical implications: The Mössbauer spectroscopy is very useful method in studying the structural environment of Fe atoms on a nearest-neighbor length scale allowing the analysis of iron-containing phases. Originality/value: The obtained examination results confirm the utility of investigation methods in analysis of microstructure of ferromagnetic glassy alloys

Preparation and selected properties of Al88Y8-xFe4+x (x = 0, 1, 2 at. %) Alloys in bulk form

The paper presents selected properties of AlYFe rapidly solidified alloys. Samples in the form of plates, obtained by pressure casting method, were subjected to structural tests in order to determine the mechanical properties of the alloys, as well as their corrosion resistance. The corrosion resistance of samples was examined using polarization tests in 3,5 % NaCl solution at 25 °C. The influence of this corrosive medium on the sample’s surface was analyzed with microscopic observations and energy-dispersive spectroscopy (EDS). The mechanical properties of alloys were determined by Vickers hardness tests. The results showed that the properties of Al88Y8-xFe4+x (x = 0, 1, 2 at. %) alloys are related to changes in the content of alloying elements

Preparation and selected properties of Al88Y8-xFe4+x (x = 0, 1, 2 at. %) Alloys in bulk form

The paper presents selected properties of AlYFe rapidly solidified alloys. Samples in the form of plates, obtained by pressure casting method, were subjected to structural tests in order to determine the mechanical properties of the alloys, as well as their corrosion resistance. The corrosion resistance of samples was examined using polarization tests in 3,5 % NaCl solution at 25 °C. The influence of this corrosive medium on the sample’s surface was analyzed with microscopic observations and energy-dispersive spectroscopy (EDS). The mechanical properties of alloys were determined by Vickers hardness tests. The results showed that the properties of Al88Y8-xFe4+x (x = 0, 1, 2 at. %) alloys are related to changes in the content of alloying elements