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The microstructure and electrochemical properties of Al–Cu–Fe alloys with the atomic compositions of Al65Cu20Fe15, Al78Cu7Fe15 and Al80Cu5Fe14Si1 have been studied. The alloys were produced by induction melting of pure elements with copper mold casting. The microstructure of the alloys was analyzed by X-ray diffraction and high-resolution transmission electron microscopy. The formation of quasicrystalline phases in the Al–Cu–Fe alloys was confirmed. The presence of intermetallic phases was observed in the alloys after crystallization in a form of ingots and plates. The electrochemical measurements were conducted in 3.5% NaCl solution. The electronic structure of the alloys was determined by X-ray photoelectron spectroscopy. The post corrosion surface of the samples was checked using a scanning electron microscope equipped with the energy-dispersive X-ray detector. It was observed that the Al65Cu20Fe15 alloy had the highest corrosion resistance. The improved corrosion resistance parameters were noted for the plate samples rather than those in the as-cast state. And the hardness of the Al65Cu20Fe15 alloy was significantly higher than the other alloy samples.

The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y alloys are presented. To reduce the number of experiments, a thermodynamic approach was applied in which the entropy and Gibbs free energy of representative alloys were optimized. The low glass-forming ability of Al-Zr-Ni-Fe-Y alloy systems was related to the crystallization of the Al3Zr phase from the melt. The structural analysis showed that phases containing Ni and Fe, such as Al19Ni5Y3, Al10Fe2Y, and Al23Ni6Y4, played a key role in the formation of amorphous alloys. According to this, the simultaneous addition of Ni/Fe and Y is important to prevent the crystallization of Al-based alloys in the melt. The formation of an amorphous phase in Al80Zr5Ni5Fe5Y5 alloys and the complete amorphization of Al85Ni5Fe5Y5 alloys were responsible for the high corrosion resistance compared with fully crystalline alloys. Moreover, the addition of Y had a significant impact on the anticorrosion properties. The XPS results showed that the alloys tended to form a passive Al2O3 and Y2O3 layer on the surface.

High-entropy ferrites (HEFs) are a new group of high-entropy oxides with unique magnetodielectric properties that offer a wide array of possibilities for high-frequency applications. Various ions were introduced at octahedral sites in the spinel structure to test the role of the high-entropy structure’s formation on its properties. The structural analysis confirmed the formation of single-phase spinel structure even for (FeCoNiMg)(FeCr)2O4 HEF. Dielectric studies showed that introducing Mg2+ and Cr3+ ions increased electrical conductivity and dielectric losses over a wide frequency range. Low frequency (from 0.8 to 1.5 GHz) studies showed that for (FeCo)Fe2O4 and (FeCoNi)Fe2O4 ferrites reflection losses (RL) are negligible, while for both (FeCoNiMg)Fe2O4 and (FeCoNiMg)( FeCr)2O4 ferrites RL higher than 90% were observed. The temperature dependence on the absorption properties was confirmed for (FeCoNiMg)(FeCr)2O4 HEF. The highest absorption window was observed for 343 K, for which RL higher than 90% appears from 1.25 to 1.5 GHz. The possibility of the 3D printing of microwave absorption composites from HEFs was also tested. It was confirmed that the addition of (FeCoNiMg)(FeCr)2O4 HEF drastically increases the absorption properties up to 85.5% at 2.72 GHz for the absorber with the same thickness as made from the pure acrylonitrile butadiene styrene (ABS). Interestingly, the EMI shielding properties of these composites are mainly related to the dielectric losses improved by the addition of entropy stabilised ferrites in 3D printed composites with various ferrite concentrations.

High entropy alloys with variable silicon content were prepared by two different methods to determine the influence of the cooling rate and chemical composition on the structure and properties of the alloys. First, the structure of the alloys was investigated using X-ray diffractometry and electron microscopy and compared with Mössbauer spectra to obtain a comprehensive description of the atom arrangement. The formation ability of the BCC and B2 phases was confirmed. The magnetic properties were examined using a vibrating sample magnetometer and Mössbauer spectroscopy. The corrosion resistance behavior was stu died by electrochemical testing. Our results show that the saturation magnetization tends to decrease with increasing silicon content and that the lowest coercive force was noted for rapidly cooled plates. The highest corrosion resistance in a 3.5% NaCl solution characterizes the AlCoCrFeNiSi0.75 alloy in the form of plates. For which Ecorr and jcorr was equal to − 0.155 V and 0.17 μA/cm2. The addition of Si led to an increase in the hardness of the ingots and plates. For example, AlCoCrFeNiSi0.75 shows 859 HV for the ingot and 727 HV for the plate.

Nanocrystalline magnetic materials are of great interest in order to meet the needs of electronics and electrical engineering. There are many possibilities to modify the synthesis parameters and chemical composition in order to obtain the most desirable magnetic properties and microstructure. The paper discusses an iron-based alloy with the addition of boron lanthanum and aluminium. The alloy was obtained by induction melting and casting with a melt-spinner. The main purpose of the work was to analyze the structure and properties of both the starting alloys in the form of ingots and the obtained tapes. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration magnetometry (VSM) and microhardness measurements using the Vickers method were carried out.

Purpose: The article presents the results of research on titanium dioxide synthesized by a sol-gel method that is an easy process enabling the control of the shape and size of particles The purpose of this article is to examine titanium dioxide nanoparticles and thin films deposited by an atomization method. Design/methodology/approach: Titanium dioxide sol was synthesized by using titanium isopropoxide as a precursor. Optical properties were measured by a UV-Vis spectrometer. Structural studies were performed by Raman spectroscopy. Qualitative analysis was performed by the EDS. Surface morphology of nanoparticles and thin films was performed by the SEM technique. Findings: The sol-gel method allows the formation of uniform nanoparticles and thin films of titanium dioxide. The atomization method is a successful method for the deposition of sol to the surface of substrates. Research limitations/implications: The next step in the research will be to investigate the obtained thin films in dye-sensitized solar cells as a semiconductive layer. Practical implications: Unique properties of produced titanium dioxide nanostructural materials have caused the interest in them in such fields as optoelectronics, photovoltaics, medicine and decorative coatings. Originality/value: Titanium dioxide thin films and nanoparticles were synthesized using the sol-gel method and then deposited by the atomization method.

Purpose: The article presents an analysis of accidents in the selected enterprise from the automotive industry. The analysis includes two workplaces: machine operator and warehouseman. Design/methodology/approach: The analysis of accidents at work in a selected production company includes the period from the beginning of 2016 to half of the 2018 year using the method based on the TOH model. This method determines three factors of accident causes: technical, organizational and human (TOH). Findings: In the paper, the workplaces analysis taking into account activities, type of work, working position and accidents at work is presented. The analysis of work accidents includes the age group, work experience etc. The TOH model determines causes related to accidental events. Research limitations/implications: The accidents at work are the result of a low or undesirable safety culture. Because of that, the safety culture should be constantly developed, maintained and continuously improved. Originality/value: Many methods and procedures can be used to investigate accidents at work. The TOH model is one of them. It determines the direct and indirect causes of accidents. Based on them, the corrective actions can be proposed and implemented.

Biodegradable magnesium alloys with Zn, Yb, Ca and Sr additions are potential materials with increased corrosion resistance in physiological fluids that ensure a controlled resorption process in the human body. This article presents the influence of the use of a high cooling rate on the corrosion behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 alloy proposed for medical applications. The microstructure of the alloy in a form of high-pressure die-casted plates was presented using scanning electron microscopy in the backscattered electrons (BSEs) mode with energy-dispersive X-ray spectrometer (EDX) qualitative analysis of chemical composition. The crystallization mechanism and thermal properties were described on the basis of differential scanning calorimetry (DSC) results. The corrosion behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 alloy was analyzed by electrochemical studies with open circuit potential (EOCP) measurements and polarization tests. Moreover, light microscopy and X-ray photoelectron spectroscopy were used to characterize the corrosion products formed on the surface of studied samples. On the basis of the results, the influence of the cooling rate on the improvement in the corrosion resistance was proved. The presented studies are novel and important from the point of view of the impact of the technology of biodegradable materials on corrosion products that come into direct contact with the tissue environment.

The effect of iron and yttrium additions on glass forming ability and corrosion resistance of Al88Y8-xFe4+x (x = 0, 1, 2 at.%) alloys in the form of ingots and melt-spun ribbons was investigated. The crystalline multiphase structure of ingots and amorphous-crystalline structure of ribbons were examined by a number of analytical techniques including X-ray diffraction, Mössbauer spectroscopy, and transmission electron microscopy. It was confirmed that the higher Fe additions contributed to formation of amorphous structures. The impact of chemical composition and structure of alloys on their corrosion resistance was characterized by electrochemical tests in 3.5% NaCl solution at 25 °C. The identification of the mechanism of chemical reactions taking place during polarization test along with the morphology and internal structure of the surface oxide films generated was performed. It was revealed that the best corrosion resistance was achieved for the Al88Y7Fe5 alloy in the form of ribbon, which exhibited the lowest corrosion current density (jcorr = 0.09 μA/cm2) and the highest polarization resistance (Rp = 96.7 kΩ∙cm2).

The effect of iron and yttrium additions on glass forming ability and corrosion resistance of Al88Y8-xFe4+x (x = 0, 1, 2 at.%) alloys in the form of ingots and melt-spun ribbons was investigated. The crystalline multiphase structure of ingots and amorphous-crystalline structure of ribbons were examined by a number of analytical techniques including X-ray diffraction, Mössbauer spectroscopy, and transmission electron microscopy. It was confirmed that the higher Fe additions contributed to formation of amorphous structures. The impact of chemical composition and structure of alloys on their corrosion resistance was characterized by electrochemical tests in 3.5% NaCl solution at 25 °C. The identification of the mechanism of chemical reactions taking place during polarization test along with the morphology and internal structure of the surface oxide films generated was performed. It was revealed that the best corrosion resistance was achieved for the Al88Y7Fe5 alloy in the form of ribbon, which exhibited the lowest corrosion current density (jcorr = 0.09 μA/cm2) and the highest polarization resistance (Rp = 96.7 kΩ∙cm2).

The aim of the work was to characterize the structure of Al65Cu20Fe15 alloy obtained with the use of conventional casting and rapid solidification-melt-spinning technology. Based on the literature data, the possibility of an icosahedral quasicrystalline phase forming in the Al-Cu-Fe was verified. Structure analysis was performed based on the results of X-ray diffraction, neutron diffraction, 57Fe M&ouml, ssbauer and transmission electron microscopy. Studies using differential scanning calorimetry were carried out to describe the crystallization mechanism. Additionally, electrochemical tests were performed in order to characterize the influence of the structure and cooling rate on the corrosion resistance. On the basis of the structural studies, the formation of a metastable icosahedral phase and partial amorphous state of ribbon structure were demonstrated. The possibility of the formation of icosahedral quasicrystalline phase I-AlCuFe together with the crystalline phases was indicated by X-ray diffraction (XRD), neutron diffraction (ND) patterns, M&ouml, ssbauer spectroscopy, high-resolution transmission electron microscopy (HRTEM) observations and differential scanning calorimetry (DSC) curves. The beneficial effect of the application of rapid solidification on the corrosive properties was also confirmed.

Amorphous and crystalline magnesium alloys, developed for medical applications – especially implantology – present the characteristics of biocompatible magnesium alloys (Mg-Zn, Mg-Zn-Ca, Mg-Ca etc.). This chapter provides a brief description of the role of magnesium in the human body and the use of Mg in medicine. It presents the concept of using magnesium alloys in medicine (advantages and limitations) and the scope of their potential applications (orthopedic implantology, cardiac surgery etc.). The chapter shows classification of magnesium alloys as potential biomaterials, due to their structure (amorphous, crystalline) and alloying elements (rare earth elements, noble metals etc.). The mechanism and in vitro degradation behavior of magnesium alloys with amorphous and crystalline structures are described. The chapter also discusses the influence of alloying elements (rare earth elements, noble metals) on the in vitro degradation process. It also presents the methods of reducing the degradation rate of magnesium alloys by modifying their surface (application of protective layers).

In this study, possibility of using different thermodynamic parameters, such as: ideal configurational entropy, mixing enthalpy, Gibbs free energy of mixing and mismatch entropy for determining chemical composition of Fe-Co based amorphous alloys was evaluated. The high role of entropy in formation of amorphous phase was confirmed, but maximization of the value of ideal configurational entropy did not allow to obtain fully amorphous alloy. The chemical composition of Fe35Co35Si11B19 amorphous alloy was determined based on minimization the value of Gibbs free energy of formation of amorphous phase – the new parameter proposed in this study. Herein, this new proposed parameter was also used to describe an influence of different chemical elements on glass forming ability of Zr, Cu and Fe based alloys. It was shown, that the Fe based amorphous alloys with the most negative value of Gibbs free energy of formation of amorphous phase were characterized by high thermal stability. The high thermal stability and glass forming ability of Fe35Co35Si11B19 amorphous alloy were confirmed by using differential thermal analysis, X-ray diffraction method, Mossbauer spectroscopy and differential scanning calorimetry. Additionally, influence of isothermal crystallization of Fe35Co35Si11B19 alloy on the structure and magnetic properties was described.

Biodegradable magnesium alloys with Zn, Yb, Ca and Sr additions are potential materials with increased corrosion resistance in physiological fluids that ensure a controlled resorption process in the human body. This article presents the influence of the use of a high cooling rate on the corrosion behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 alloy proposed for medical applications. The microstructure of the alloy in a form of high-pressure die-casted plates was presented using scanning electron microscopy in the backscattered electrons (BSEs) mode with energy-dispersive X-ray spectrometer (EDX) qualitative analysis of chemical composition. The crystallization mechanism and thermal properties were described on the basis of differential scanning calorimetry (DSC) results. The corrosion behavior of Mg60Zn20Yb15.7Ca2.6Sr1.7 alloy was analyzed by electrochemical studies with open circuit potential (EOCP) measurements and polarization tests. Moreover, light microscopy and X-ray photoelectron spectroscopy were used to characterize the corrosion products formed on the surface of studied samples. On the basis of the results, the influence of the cooling rate on the improvement in the corrosion resistance was proved. The presented studies are novel and important from the point of view of the impact of the technology of biodegradable materials on corrosion products that come into direct contact with the tissue environment.

The spontaneous oxidation of a magnetite surface and shape design are major aspects of synthesizing various nanostructures with unique magnetic and electrical properties, catalytic activity, and biocompatibility. In this article, the roles of different organic modifiers on the shape and formation of an oxidized layer composed of maghemite were discussed and described in the context of magnetic and electrical properties. It was confirmed that Fe3O4 nanoparticles synthesized in the presence of triphenylphosphine could be characterized by cuboidal shape, a relatively low average particle size (9.6 ± 2.0 nm), and high saturation magnetization equal to 55.2 emu/g. Furthermore, it has been confirmed that low-frequency conductivity and dielectric properties are related to surface disordering and oxidation. The electric energy storage possibility increased for nanoparticles with a disordered and oxidized surface, whereas the dielectric losses in these particles were strongly related to their size. The cuboidal magnetite nanoparticles synthesized in the presence of triphenylphosphine had an ultrahigh electrical conductivity (1.02 × 10−4 S/cm at 10 Hz) in comparison to the spherical ones. At higher temperatures, the maghemite content altered the behavior of electrons. The electrical conductivity can be described by correlated barrier hopping or overlapping large polaron tunneling. Interestingly, the activation energies of electrons transport by the surface were similar for all the analyzed nanoparticles in low- and high-temperature ranges.

The corrosion activity of amorphous plates of Ca60Mg15Zn25 alloy was investigated. The biocompatible elements were selected for the alloy composition. The electrochemical corrosion and immersion tests were carried out in a multi-electrolyte fluid and Ringer's solution. Better corrosion behavior was observed for the samples tested in a multi-electrolyte fluid despite the active dissolution of Ca and Mg in Ringer's solution. The experimental results indicated that reducing concentration of NaCl from 8.6 g/dm3 for Ringer's solution to 5.75 g/dm3 caused the decrease of the corrosion rate. The volume of the hydrogen evolved after 480 min in Ringer's solution (40.1 ml/ cm2) was higher in comparison with that obtained in a multi-electrolyte fluid (24.4 ml/cm2). The values of opencircuit potential (EOCP) for the Ca60Mg15Zn25 glass after 1 h incubation in Ringer's solution and a multielectrolyte fluid were determined to be −1553 and −1536 mV vs. a saturated calomel electrode (SCE). The electrochemical measurements indicated a shift of the corrosion current density (jcorr) from 1062 μA/cm2 for the sample tested in Ringer's solution to 788 μA/cm2 for the specimen immersed in a multi-electrolyte fluid. The corrosion products analysis was conducted by using the X-ray photoelectron spectroscopy (XPS). The corrosion products were identified to be CaCO3, Mg(OH)2, CaO, MgO and ZnO. The mechanism of corrosion process was proposed and described based on the microscopic observations. The X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) also indicated that Ca(OH)2, CaCO3, Zn(OH)2 and Ca(Zn(OH)3)2·2H2O mainly formed on the surface of the studied alloy., The work was supported by National Science Centre under research project no.: 2013/09/B/ST8/02129 .

This article discusses the influence of the thickness of TiO2 films deposited onto MgCa2Zn1 and MgCa2Zn1Gd3 alloys on their structure, corrosion behavior, and cytotoxicity. TiO2 layers (about 200 and 400 nm thick) were applied using magnetron sputtering, which provides strong substrate adhesion. Such titanium dioxide films have many attractive properties, such as high corrosion resistance and biocompatibility. These oxide coatings stimulate osteoblast adhesion and proliferation compared to alloys without the protective films. Microscopic observations show that the TiO2 surface morphology is homogeneous, the grains have a spherical shape (with dimensions from 18 to 160 nm). Based on XRD analysis, it can be stated that all the studied TiO2 layers have an anatase structure. The results of electrochemical and immersion studies, performed in Ringer&rsquo, s solution at 37 &deg, C, show that the corrosion resistance of the studied TiO2 does not always increase proportionally with the thickness of the films. This is a result of grain refinement and differences in the density of the titanium dioxide films applied using the physical vapor deposition (PVD) technique. The results of 24 h immersion tests indicate that the lowest volume of evolved H2 (5.92 mL/cm2) was with the 400 nm thick film deposited onto the MgCa2Zn1Gd3 alloy. This result is in agreement with the good biocompatibility of this TiO2 film, confirmed by cytotoxicity tests.

Fe-based nanocrystalline alloys were prepared by the melt-spinning technique and characterized by X-ray diffraction, magnetostatic and Mössbauer effect methods. The Mössbauer spectroscopy allows to study the local environment of the Fe atoms in the investigated Fe80 xNixB20 (x 8, 16, 24, 28) compounds and showing the changes in the structure due to the changing of Ni addition. Combination of X-ray diffraction and Mössbauer spectroscopy results confirm formation of different number of phase complex, including the -FeNi, -FeNi, FeB, Fe2B, Fe3B in the investigated materials together with increase of Ni content.

Magnesium alloys are considered as potential biomaterials for use in orthopedic implantology. The main barrier to the use of Mg alloys in medicine is their overly fast and irregular degradation in body fluids. The use of protective calcium phosphate coatings to increase the corrosion resistance of Mg alloy (AM50 alloy: 4 wt.% Al, 0.3 wt.% Mn, 0.2 wt.% Zn, rest Mg) was examined in this study. The scientific goal of the study was the assessment of the influence of calcium phosphate layer morphology on the corrosion process in Ringer&rsquo, s solution. Modification of the coating morphology was obtained by changing the chemical composition of the phosphatizing bath using NaOH (NaAM50 sample) or ZnSO4 (ZnAM50 sample). In practice, a more dense and uniform coating could be obtained by the immersion of AM50 alloy in a solution containing ZnSO4 (ZnAM50 sample). In this study, an adhesion test performed on the ZnAM50 sample indicated that the critical load was 1.35 N. XRD phase analysis confirmed that the obtained coatings included dicalcium phosphate dihydrate (CaHPO4*2H2O). The coatings prepared on the NaAM50 and ZnAM50 samples are effective barriers against the progress of corrosion deeper into the substrate. After 120 h immersion in Ringer&rsquo, s solution, the volume of the evolved hydrogen was 5.6 mL/cm2 for the NaAM50 and 3.4 mL/cm2 for the ZnAM50 sample.

In this work, the compositions of Al-Ni-Fe alloys were determined based on thermodynamic parameters optimization. Decagonal quasicrystalline phase D -Al70.83Fe9.83Ni19.34 was identified in the alloy with the highest Gibbs free energy of solid solution formation, i.e., Al71Ni24Fe5. According to this, the configurational entropy and enthalpy of solid solution formation must reach equilibrium to form quasicrystals in Al-Ni-Fe alloys. Differential thermal analysis and X-ray diffraction were used to describe the crystallization mechanism as a function of Fe concentration. 57Fe Mossbauer spectroscopy was used to describe the Fe local environment in crystalline alloys and quasicrystals. Moreover, the influence of quasicrystalline phases on improving the corrosion resistance was investigated. Quasicrystalline Al71Ni24Fe5 alloy had a six-times lower corrosion rate than its crystalline counterparts. Although this alloy showed the best corrosion resistance, all high-pressure cast Al-Fe-Ni alloys displayed improved corrosion resistance.

The main aim of this paper was to produce amorphous ribbons with specified composition with the use of various process parameters and X-ray qualitative and quantitative phase analysis after casting and heat treating. Station for ultra-fast cooling of the molten alloy with high vacuum pumps designed for the production of metallic glasses in the form of ribbons with the use of Buhler Melt Spinner SC was used. The X-ray qualitative and quantitative phase analysis, microscopic observation, microhardness and thermal properties tests of the investigated ribbons were conducted. Based on experimental data the discussion on the correlation between casting process parameters, phase and quantitative composition and heat treatment was carried out.

The paper presents the structural analysis of Fe62􀀀xCoxNb8B30 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.

Stabilization and modification of magnetite nanoparticles synthesized by the co-precipitation method were presented in these studies. The role of chemical treatment on the structure and properties of Fe3O4 nanoparticles was described. It was noted, that the functionalization of nanoparticles surface by malonic acid has a negative impact on the catalytic activity in Fenton and photo-Fenton processes. The decolorization rate decreases from 86% to 35% and from 93% to 85.5 % at the same reaction time for these processes, respectively. However, the magnetite nanoparticles stabilized by malonic acid have higher saturation magnetization and electrical conductivity. These changes were related to the removal of the oxidized surface layer and to the stabilization of iron ions by malonic acid molecules, which was confirmed by the analysis of Mossbauer spectra. The proposed modification also allowed to reduce the size of the agglomerated nanoparticles 10 times and to produce stable Fe3O4 NPs.

The work presents preparation methods, structure characterization and mechanical properties analysis of Mg-based bulk metallic glasses in as-cast state and after crystallization process. The studies were performed on Mg60Cu30Y10 and Mg37Cu36Ca27 glassy alloys in the form of plates and rods. The X-ray diffraction investigations revealed that the tested samples with different thicknesses and shapes were amorphous. The characteristics of the fractured surfaces showed mixed fractures with the “river” and “mirror” patterns, which are characteristic for the glassy materials and some “smooth” areas. The samples of Mg37Cu36Ca27 alloy presented a two-stage crystallization process, but addition of Y caused a single stage crystallization behavior. Qualitative phase analysis from the X-ray data of examined alloys annealed at 473 K enabled the identification of Mg, Mg2Cu, Cu2Mg and CaCu crystalline phases. The changes of compressive strength as a function of annealing temperature for studied rods were stated. The best mechanical properties including microhardness and compressive strength were obtained for the alloy with the addition of Y in as-cast state.

In this paper the influence of copper addition on the formation of the amorphous phase and the nanocrystallization process of Fe79.8−xCo2CuxMo0.2Si4B14 (x = 0, 0.25, 0.5, 0.75, 1, 1.5, 2) ribbons was described. The formation of crystalline phases was described using differential scanning calorimetry, X-ray diffractometry, Mossbauer spectroscopy and transmission electron microscopy. It was confirmed that the addition of copper decreases the glass forming ability, while facilitating the process of nanocrystallization. The analysis of the Avrami exponent allowed to state, that for fully amorphous alloys the crystallization of the α-Fe phase is associated with diffusion-controlled growth with decreasing nucleation rate and the Fe2B phase with interface controlled growth with increasing nucleation rate. Additionally, with increasing copper addition onset temperature of crystallization of α-Fe phase shifts to lower values, whereas for second, Fe2B phase, these changes are not so visible. Optimization of the annealing process of toroidal cores made from amorphous ribbons with different copper content allowed to obtain nanocrystalline, soft magnetic materials characterized by low coercivity ~9 A/m and high saturation induction of about 1.6 T. Analysis of transmission electron microscope images and electron diffraction confirmed that high magnetic parameters are related to the coexistence of the amorphous and nanocrystalline phases, which was confirmed also by Mossbauer spectroscopy.

A new class of CaZn-based bulk glassy alloys with minor addition of boron and enhanced corrosion resistance for use in bioresorbable materials is introduced. The CaMgZnYbB alloys represent a new family of biomaterials with potential applications in orthopedic implants with controlled degradation rates and corrosion in the human body. The effect of substituting Yb for B in the structure on the corrosion and mechanical properties of quinternary Ca32Mg12Zn38Yb18-xBx (x = 1,2,3 at.%) alloys was investigated using X-ray diffraction, high-resolution transmission electron microscopy, differential scanning calorimetry, immersion and electrochemical polarization, compressive tests, and hardness measurements. The corrosion behavior was also evaluated using electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Microstructural investigations showed that the Ca32Mg12Zn38Yb16B2 alloy was mainly amorphous, while small reflections from nanocrystals were observed in Ca32Mg12Zn38Yb17B1 and Ca32Mg12Zn38Yb15B3. Electrochemical polarization and immersion tests in Ringer's solution at 37 °C revealed that the CaMgZnYbB alloys had significantly higher corrosion resistance than CaMgZn alloys. Electrochemical impedance spectroscopy of alloys showed only single capacitive loops. The corrosion products were identified as CaO, MgO, Mg(OH)2, and CaCO3. The compressive strengths of the alloys from 220 MPa to 283 MPa were suitable for implant applications.

The local atomic structure of the Fe 80 B 20 , Fe 70 Nb 10 B 20 and Fe 62 Nb 8 B 30 glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe–Fe, Fe–B, Fe–Nb and Nb–B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe 3 B, Fe 23 B 6 and bcc Fe structures are also discussed.

The ferromagnetic Fe-based amorphous alloys were studied due to properties for soft magnetic applications. Depending on different Nb addition, the formation of crystalline phases after annealing of amorphous Fe80􀀀xB20Nbx (x = 4, 6, 10) alloys was studied. The crystallization products as well as the phase structure were determined using the Mössbauer spectrometry combined with differential scanning calorimetry and magnetic measurements. The addition of Nb caused a shift of crystallization process towards higher temperatures and induced changes in coercive force and decreased the saturation magnetization. It was found that Nb addition changed the crystallization process from single crystallization for Fe76B20Nb4 alloy to binary crystallization in the Fe74B20Nb6 and Fe70B20Nb10 glasses. The annealing process at the onset crystallization temperature induced complex phase formation including the -Fe, Fe3B, and Fe2B phases for alloys x = 4, 6[…]

Recently bulk amorphous alloys have attracted great attention due to their excellent magnetic properties. The glass-forming ability of bulk amorphous alloys depends on the temperature difference (Δ T x ) between glass transition temperature ( T g ) and crystallization temperature ( T x ). The increase of Δ T x causes a decrease of the critical cooling rate ( V c ) and growth of the maximum casting thickness of bulk amorphous alloys. The aim of the present paper is to characterize the structure, the thermal stability and magnetic properties of Fe 36 Co 36 B 19 Si 5 Nb 4 bulk amorphous alloys using XRD, Mossbauer spectroscopy, DSC and VSM methods. Additionally the magnetic permeability μ i (at force H ≈ 0.5 A/m and frequency f ≈ 1 kHz) and the intensity of disaccommodation of magnetic permeability Δ μ / μ ( t 1 ) (Δ μ = μ ( t 1 = 30 s) − μ ( t 2 = 1800 s)), have been measured, where μ is the initial magnetic permeability measured at time t after demagnetisation, the Curie temperature T C and coercive force H c of rods are also determined with the use of a magnetic balance and coercivemeter, respectively. Fe–Co–B–Si–Nb bulk amorphous alloys were produced by pressure die casting with the maximum diameters of 1 mm, 2 mm and 3 mm. The glass transition temperature ( T g ) of studied amorphous alloys increases from 807 K for a rod with a diameter of 1 mm to 811 K concerning a sample with a diameter of 3 mm. The crystallization temperature ( T x ) has the value of 838 K and 839 K for rods with the diameters of 1 mm and 3 mm, respectively. The supercooled liquid region (Δ T x = T x − T g ) has the value of about 30 K. These values are presumed to be the origin for the achievement of a good glass-forming ability of the Fe–Co–B–Si–Nb bulk amorphous alloy. The investigated amorphous alloys in the form of rods have good soft magnetic properties (e.g. M s = 1.18–1.24 T). The changes of crystallization temperatures and magnetic properties as a function of the diameter of the rods (time of solidification) have been stated.

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.