In this work, the four high entropy CoCrFeNiX alloys (X=Nb,Mo,B,Si) were prepared by induction melting to comparatively analyze their structure, nanomechanical properties, and corrosion resistance. The CoCrFeNiNb and CoCrFeNiMo alloys were composed of FCC solid solution and intermetallic phases (TM)2Nb and Cr-Mo-TM. In the case of the CoCrFeNiB alloy, a complex phase structure was revealed, consisting of FCC solid solution and three types of borides. In turn, the addition of Si substantially altered the phase composition of the CoCrFeNi alloy, resulting in the formation of two intermetallic phases. The corrosion behaviour of the alloys was studied in 3.5 and 5% NaCl solutions. The highest corrosion resistance was characteristic for the CoCrFeNiSi alloy, which showed the most uniform chemical element distribution, showing the lowest corrosion current density and the highest positive corrosion potential values in both environments used. For measurements in a 5% NaCl solution, icorr and Ecorr were equal to 0.24 mu A/cm2 and -0.136 V. The least favourable corrosion parameters were recorded for the CoCrFeNiMo alloy. The results of EIS measurements confirmed the high protective abilities of the passive film formed on the CoCrFeNiSi alloy surface. The SKPFM map of the Volta potential differences showed that the Cr-Mo-TM phase with a high molybdenum content was less noble than the FCC solid solution. Similarly, the Nirich FCC phase was more noble compared to the (TM)2Nb phase with a high niobium content for the CoCrFeNiNb alloy. The highest strength properties were shown by the alloys with the addition of metalloids. For the CoCrFeNiSi alloy, the highest nanohardness value was obtained (above 15 GPa), while the CoCrFeNiB showed the highest Young's modulus (above 275 GPa).

In this work, the effect of minor Cr addition on the thermal stability, crystallisation process, crystal structure, catalytic, magnetic and anti-corrosion properties of Fe86-xCrxB14 (x = 1, 3, 5) melt-spun metallic ribbons has been studied. The thermal analysis determined the characteristic crystallisation temperatures, thermal stability and average activation energy of the alpha-Fe phase crystallisation. To optimise the magnetic properties (magnetic induction Br, coercivity Hc, core power losses Ps), the amorphous ribbons in the form of wounded toroidal cores were subjected to 20 min of isothermal annealing (260-420 degrees C). The least lossy materials were obtained at 320 degrees C with Hc = 6.51-12.9 A/m, Ps(1T@50Hz) = 0.13-0.21 W/kg, Bs = 1.03-1.41T, mu ' = 1889-2289 and characterised as nanocomposite where alpha-Fe nanocrystals are immersed in the amorphous matrix. Magnetic properties deteriorate due to successive Cr additions. However, the electrochemical studies confirmed the enhancive effect of Cr on the anti-corrosion properties. Moreover, due to the relaxation process and the formation of a passivating layer, the anti-corrosion properties improved even more after the vacuum- and air-annealing process. Lastly, the materials exhibit catalytic properties in the photo-Fenton-like process of Methylene Blue degradation, achieving a dye reduction of 60-80 % after 60 min, enabling their dual-use as magnetic-catalytic materials.

Medium-entropy alloys (MEAs) exhibit properties comparable or even superior to high-entropy alloys (HEAs). Due to their very good resistance in thermomechanical conditions and corrosive environments and unique electrical and magnetic properties, medium-entropy alloys are good candidates for coating applications. One of the most economically effective methods of producing metallic coatings is electrodeposition. In this work, the structure of an electrodeposited CoFeNi medium-entropy alloy coating on a copper substrate from a metal chlorides solution (FeCl2 ∙ 4H2O + CoCl2 ∙ 6H2O + NiCl2 ∙ 6H2O) with the addition of boric acid (H3BO3) was investigated. The coating was characterized by a nanocrystalline structure identified by transmission electron microscopy examination and X-ray diffraction methods. Based on XRD and TEM, the face-centered cubic (FCC) phase of the CoFeNi MEA coating was identified. The high corrosion resistance of the MEA coating in a 3.5% NaCl environment at 25 °C was confirmed by electrochemical tests.

The corrosion resistance and mechanisms of the Mg72Zn27Pt1 alloy with different structures (amorphous and crystalline) were investigated in Hanks’ solution at 37 °C. It was found that the corrosion current density of crystalline Mg72Zn27Pt1 is 15 times higher than that of amorphous Mg72Zn27Pt1. The obtained results also suggest that the same electrochemical reactions occur during corrosion of both variants, but the main difference is the propagation of cracks in the crystalline Mg72Zn27Pt1. No cracks are detected during corrosion of amorphous Mg72Zn27Pt1. The results published in the literature would allow us to assume that cracking could be attributed to an increase in mechanical deformation due to hydrogen uptake by the crystalline Mg72Zn27Pt1.

In this work, the structure and selected properties of newly developed Al-Cr-Pd (72 at% of Al, 24 at% of Cr, 4 at% of Pd) and Al-Fe-Pd (72 at% of Al, 24 at% of Fe, 4 at% of Pd) alloys in the form of ingots were characterized. The structure of the alloys was described on X-ray diffraction, transmission electron microscopy, and scanning electron microscopy studies. The Al-Cr-Pd and Al-Fe-Pd alloys were examined for thermal properties (differential thermal analysis), corrosion resistance (electrochemical and scanning Kelvin probe force microscopy studies), and mechanical properties (Vickers hardness and wear resistance). Both alloys were characterized by a multiphase structure with the structurally complex intermetallics. The presence of decagonal electron diffraction (DAlPdCr) for the Al-Cr-Pd alloy was confirmed by transmission electron microscopy. The Al-Cr-Pd alloy showed a higher tendency to passivate than the Al-Fe-Pd alloy in the 3.5 % NaCl solution environment. However, the oxide layer on Al-Cr-Pd was discontinuous and less protective against further corrosion progression, as indicated by the higher corrosion current density for this alloy. For both alloys, a high contrast of Volta potentials was identified between the phases with and without palladium, which may favour the formation of galvanic microcells. The AlFe-Pd alloy showed a higher average hardness and a greater resistance to wear than the Al-Cr-Pd alloy.

In this work, a series of novel high-entropy alloys CoCrFeNiSiVx (x = 0.25; 0.5; 0.75; 1.0) with an intermetallic compound structure was proposed. The effect of vanadium addition on the structure, as well as selected mechanical and corrosion properties, was investigated. In the case of the CoCrFeNiSiV0.25 alloy, the structural analysis revealed the formation of a dual-phase structure consisting of Fe1.812V0.907Si0.906-type and Fe5Ni3Si2-type intermetallic phases. The increase in vanadium concentration results in the crystallization of one Fe1.812V0.907Si0.906 intermetallic phase detected by the X-ray diffraction method. The increase in vanadium content had a beneficial influence on the corrosion resistance of CoCrFeNiSiVx alloys in 3.5% NaCl. The CoCrFeNiSiV alloy exhibited the lowest corrosion current density of 0.17 μA/cm2 and the highest corrosion potential of −0.228 V. The hardness of the alloys investigated increased with vanadium content, reaching 1006 HV for the equimolar alloy. In turn, the lowest friction coefficient of 0.63 ± 0.06 was obtained for the CoCrFeNiSiV0.75 alloy. The abrasive, fatigue, and oxidative wear were identified as the main wear mechanisms.

In this work, CoCrFeNiNbx (x = 0.25, 0.45 and 0.65) high entropy alloys were prepared by two different methods to determine the effect of cooling rate and the niobium content on the structure and properties of ingots and plates. The structure was investigated extensively using X-ray diffraction, scanning electron microscopy, and Mössbauer spectroscopy. The results confirmed the dual-phase structure, consisting of the FCC solid solution and the Laves phase. The increase in niobium content changed the microstructure from hypoeutectic (x = 0.25 and 0.45) to hypereutectic (x = 0.65). The high cooling rate during solidification from the liquid state enabled the formation of ultrafine eutectic structures with an average lamellae thickness of only 130 ± 9 nm in the CoCrFeNiNb0.65 plate. The corrosion behaviour of the alloys was studied in solutions of 3.5% NaCl and 3.5% NaCl + H3BO3. The beneficial effect of increasing the niobium content in as-cast CoCrFeNiNbx alloys on the corrosion resistance was confirmed in both environments. Furthermore, the alloys solidified with a higher cooling rate exhibited a lower corrosion susceptibility in the 3.5% NaCl solution. The results of the EIS study indicated that a higher content of niobium contributed to the formation of a more stable and compact passivation layer. The hardness of the CoCrFeNiNbx alloys increased with a higher niobium content, achieving the highest value of 669 HV1 for the CoCrFeNiNb0.65 plate. The increase in the cooling rate positively affected the tribological properties of the CoCrFeNiNbx alloys, contributing to the decrease in the friction coefficient for the CoCrFeNiNb0.25 and CoCrFeNiNb0.45 plates.

The aim of this work was to investigate the structure and corrosion behavior of Al79Ni5Fe5Y11, Al79Ni5Fe11Y5, Al79Ni11Fe5Y5 and Al79Ni7Fe7Y7 alloys prepared by different cooling rates from the liquid state: slow-cooled ingots, cast into water-cooled copper mold plates, and melt-spun ribbons at the casting temperatures of 1150, 1200 and 1400 degrees C. In the case of Al79Ni11Fe5Y5 (1200 degrees C) and Al79Ni5Fe5Y11 (1400 degrees C) alloys in the form of melt-spun ribbons, the amorphous structure was confirmed by XRD, TEM and DSC. Increasing the cooling rate from the liquid state by casting into a water-cooled copper mold resulted in an ultrafine-grained structure. Electrochemical tests in 3.5 % NaCl aqueous solution at 25 degrees C indicated that corrosion resistance increases with a higher cooling rate from the liquid state, especially for amorphous alloys.

Zirconium-based alloys are highly regarded by the research community for their exceptional corrosion resistance, thermal stability, and mechanical properties. In our work, we investigated two newly developed alloys, Zr42.42Cu41.18Al9.35Ag7.05 and Zr46.81Cu35.44Al10.09Ag7.66, in the form of ingots and ribbons. In the course of our investigation, we conducted a comprehensive structural and thermal analysis. In addition, an examination of the corrosion activity encompassing electrochemical studies and an analysis of the corrosion mechanisms was carried out. To further evaluate the performance of the materials, tests of their mechanical properties were performed, including microhardness and resistance to abrasive wear. Structural analysis showed that both alloys studied had a multiphase, crystalline structure with intermetallic phases. The samples in the form of ribbons showed improved corrosion resistance compared to that of the ingots. The ingot containing a higher content of copper Zr42.42Cu41.18Al9.35Ag7.05 was characterized by better corrosion resistance, while showing lower average hardness and a higher degree of abrasive wear based on SEM observations after pin-on-disc tests.

In this study, thin ribbons of amorphous Mg72Zn27Pt1 and Mg72Zn27Ag1 alloys with potential use in biomedicine were analyzed in terms of the crystallization mechanism. Non-isothermal annealing in differential scanning calorimetry (DSC) with five heating rates and X-ray diffraction (XRD) during heating were performed. Characteristic temperatures were determined, and the relative crystalline volume fraction was estimated. The activation energies were calculated using the Kissinger method and the Avrami exponent using the Jeziorny–Avrami model. The addition of platinum and silver shifts the onset of crystallization towards higher temperatures, but Pt has a greater impact. In each case, Eg > Ex > Ep (activation energy of the glass transition, the onset of crystallization, and the peak, respectively), which indicates a greater energy barrier during glass transition than crystallization. The highest activation energy was observed for Mg72Zn27Pt1 due to the difference in the size of the atoms of all alloy components. The crystallization in Mg72Zn27Ag1 occurs faster than in Mg72Zn27Pt1, and the alloy with Pt has higher (temporary) thermal stability. The Avrami exponent (n) values oscillate in the range of 1.7–2.6, which can be interpreted as one- and two-dimensional crystal growth with a constant/decreasing nucleation rate during the process. Moreover, the lower the heating rate, the higher the nucleation rate. The values of n for Mg72Zn27Pt1 indicate a greater number of nuclei and grains than for Mg72Zn27Ag1. The XRD tests indicate the presence of α-Mg and Mg12Zn13 for both Mg72Zn27Pt1 and Mg72Zn27Ag1, but the contribution of the Mg12Zn13 phase is greater for Mg72Zn27Ag1

Magnesium-based materials are an interesting solution in terms of medical applications. Alloys that are hard to obtain via standard means may be manufactured via mechanical alloying (MA), which allows the production of materials with complex a chemical composition and non-equilibrium structures. This work aimed to investigate materials obtained by the MA process for 5, 8, 13, and 20 h in terms of their phase composition and changes during heating. The results of thermal XRD analysis were in the temperature range between 25 and 360 °C, which revealed MgZn2, PrZn11, Ca2Mg5Zn13, and Ca phases as well as α-Mg and α-Zn solid solution. The structural analysis features the powder morphology of the analyzed samples, showing cold-welding and fracturing processes leading to their homogenization, which is supported by the EDS results. The base Mg-Zn-Ca alloy was modified by different additions, but a thorough analysis of the influence of praseodymium on its thermal properties has not yet been performed. We chose to focus on Pr addition because it belongs to low-toxicity rare earth metals, which is an essential feature of biomaterials. Also, the Ca2Mg5Zn13 phase is not fully known, as there are no crystallographic data (hkl). Therefore, the investigation is important and scientifically justified.

In this study, the structure of Al65Zr20Fe15 and Al71Zr24Fe5 alloys was studied using neutron diffraction and SEM with EDX maps. This paper presents the electrochemical measurement results performed in 3.5% NaCl, H3BO3, and 3.5% NaCl+H3BO3 solutions at 40°C. The Al71Zr24Fe5 alloy showed higher corrosion resistance in acidic solution, whereas the Al65Zr20Fe15 alloy was more resistant in 3.5%NaCl+H3BO3. Moreover, the corrosion behavior was described for the samples immersed for 8 weeks in 3.5%NaCl at 40°C. SKPFM indicated high Volta potential differences between Al-Zr and Al-Fe-Zr phases. Moreover, the higher wear resistance for Al65Zr20Fe15 compared to the Al71Zr24Fe5 alloy was demonstrated.

The influence of copper addition on the structure and selected properties of AlCoCrFeNiSi0.5Cux high-entropy alloys is described. Slowly cooled ingots were prepared by induction melting, and the samples in the form of plates were obtained by pressure casting. The conducted structural studies confirmed the presence of BCC/B2 phase. Microsegregation in the ingots was associated with the formation of intermetallic Cr3Si and Fe5Si3 phases. An increase in the cooling rate stopped segregation by reducing the mobility of Cr and Si. The hyperfine magnetic field distributions indicated the formation of the BCC Fe(Co,Ni,Si,Cr) solid solution for alloys in the form of plates. The lowest corrosion-current density (0.04 μA/cm2) in 3.5

The low glass-forming ability of aluminium-based metallic glasses significantly limits their development and preparation. This paper updates the current state of knowledge by presenting the results of structural studies of two newly-developed Al 79 Ni 5 Fe 5 Y 11 and Al 79 Ni 11 Fe 5 Y 5 alloys with a reduced aluminium content (< 80 at.%). The alloys were produced by conventional casting (ingots) and melt-spinning (ribbons). Structural characterization was carried out for bulk ingots first, and then for the melt-spun ribbons. The ingots possessed a multiphase crystalline structure, as confirmed by X-ray diffraction and scanning electron microscopy observations. The amorphous structure of the melt-spun ribbons was determined by X-ray diffraction and transmission electron microscopy. SEM observations and EDX element maps of the cross-section of melt-spun ribbons indicated a homogeneous elemental composition. Neutron diffraction revealed the presence of nanocrystals in the amorphous matrix of the melt-spun ribbons. DSC data of the melt-spun ribbons showed exothermic events corresponding to the first crystallization at temperatures of 408 °C and 387 °C for Al 79 Ni 5 Fe 5 Y 11 and Al 79 Ni 11 Fe 5 Y 5 , respectively.

Al-Y-Fe amorphous and nanocrystalline alloys are characterized by a unique collection of diverse properties that are influenced by various factors, including heat treatment. In this paper, the effect of heat treatment on the structural changes and selected properties of Al-Y-Fe metallic glasses in the as-spun state is investigated. The structure of the Al88Y7Fe5 and Al88Y6Fe6 alloys was examined by means of X-ray diffraction (XRD) and Mossbauer spectroscopy (MS). Corrosion resistance of the samples was characterized using polarization tests in a 3.5% NaCl solution at 25 degrees C. The effect of sodium chloride on the surface was studied with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The magnetic properties of Al-based alloys were explored using a vibrating sample magnetometer (VSM). It was revealed that the tested alloys show better properties after annealing than in the as-spun state. The annealing of the Al88Y7Fe5 and Al88Y6Fe6 alloys in the temperature range of 200 to 300 degrees C improved the magnetic properties and corrosion resistance of these materials. After 3600 s, better EOCP values were recorded for the Al88Y6Fe6 and Al88Y7Fe5 alloys after annealing at 300 degrees C and 200 degrees C, respectively. On the basis of the polarization tests, it was concluded that the electrochemical properties are better for Al88Y6Fe6 alloys after annealing at 300 degrees C.

In order to investigate the effect of the milling time on the corrosion resistance of the Mg65Zn30Ca4Pr1 alloy, powders of the alloy were prepared and milled for 13, 20, and 70 hours, respectively. The samples were sintered using spark plasma sintering (SPS) technology at 350 & DEG;C and pressure of 50 MPa. The samples were subjected to potentiodynamic immersion tests in Ringer's solution at 37 & DEG;C. The obtained values of Ecorr were -1.36, -1.35, and -1.39 V, with polarization resistance Rp = 144, 189, and 101 & omega; for samples milled for 13, 20 and 70 h, respectively. The samples morphology showed cracks and pits, thus signaling pitting corrosion.

The high entropy AlCoFeNiTi and AlCoFeNiTiSi alloys were prepared by two methods to determine the influence of the cooling rate on the structure and properties. The Mossbauer spectra of AlCoFeNiTi alloys showed the coexistence of a nonmagnetic part with a magnetic hyperfine portion. The spectra for AlCoFeNiTiSi alloy in an as-cast and plate states contain only nonmagnetic components. The X-ray dif-fraction analysis confirmed that the silicon addition drastically changes the phase composition of AlCoFeNiTi alloy. Whereas alloy without Si was characterised by the coexistence of L21 and BCC phases, the addition of silicon resulted in the formation of Ti-rich HCP and Al-rich B2 phases. AlCoFeNiTi plate exhibits a high saturation magnetisation value of 29.83 emu/g and the best corrosion resistance (polarisation re-sistance of about 38.6 k Omega cm2 and corrosion current density of 0.77 mu A/cm2). The highest hardness (1096 HV) was achieved for AlCoFeNiTiSi plate, which is related to the phase composition changes generated by Si addition. The influence of the Si addition on the properties of studied alloys was also confirmed in the decolourisation of Rhodamine B using a modified photo-Fenton process. The decolourisation efficiency within 60 min was 92% for AlCoFeNiTiSi alloy, and 95.5% for the AlCoFeNiTi alloy.(c) 2022 Elsevier B.V. All rights reserved.

This work used a thermodynamic approach to design and investigate new complex compositional Al-Ni-Fe(Cr,Cu) alloys based on aluminum. This work tends to understand the change in microstructure during the rapid solidification process and to evaluate the anticorrosion and nanomechanical properties of the developed alloys. Optimizing thermodynamic parameters such as configurational entropy and Gibbs free energy was used to predict the chemical composition of the studied alloys. The samples were cooled in two ways. The ingots were slowly cooled, while the plates were cast using fast cooling by the high-pressure die-casting method. The presence of a quasicrystalline decagonal phase D-Al71Ni24Fe5 was identified together with crystalline Al3Ni, Al3Ni2, and Al9Ni1.3Fe0.7 phases for the rapidly solidified Al72Ni24Fe4 alloy. The best electrochemical parameters were observed for the Al72Ni24Fe2.5Cr1.5 alloy. The local galvanic microcells were formed in the studied alloys due to large potential differences (> 50 mV) between the Al-Ni and Al-Ni-Fe phases. The highest average indentation hardness values were observed for Al72Ni24Fe4 (9.98 & PLUSMN; 1.75 GPa) after normal and rapid solidification. The higher ductility of the Al72Ni24Cr1.5Fe2.5 alloy compared to Al72Ni24Fe4 and Al72Ni24Cu1.5Fe2.5 could be confirmed by the lowest average hardness and Young's modulus values.

Flower-like magnetite nanoflowers (Fe3O4 NFs) were synthesized in this study using a new, highly scalable, modified co-precipitation method. The heterogeneous photo-Fenton process was optimized for the degradation of Rhodamine B using sodium percarbonate as an alternative source of H2O2. The low dosage of NPs (0.6 mg/ml) can ensure the high Rhodamine B degradation of about 93.6% at pH 4 and sodium percarbonate concentration of 8.3 mg/ml. Studies confirm the high cyclic stability of Fe3O4 NFs and the possibility of using optimized reaction condition in the degradation of Lissamine Green B (97.3%) and Naphthol Green B (61.8%). Moreover, it was confirmed that O2  and HO & BULL; are the primary radicals oxidizing Rhodamine B, while the ultrafast Lissamine Green B degradation corresponds to their oxidation by O2 . Finally, surface functionalization was confirmed as one of the most critical parameters in designing catalysts for heterogeneous photo-Fenton processes. The study confirms that in the case of surface functionalization, the degradation of dyes is slowed down (reduction of active sites on the magnetite surface by the organic molecules). Accordingly, the ultrafine, spherical-shaped magnetite nano-particles functionalized by thrietylene glycol were characterized by above 3 times lower catalytic activity than unfunctionalized Fe3O4 NFs.

The low glass-forming ability of aluminium-based metallic glasses significantly limits their development and preparation. This paper updates the current state of knowledge by presenting the results of structural studies of two newly-developed Al79Ni5Fe5Y11 and Al79Ni11Fe5Y5 alloys with a reduced aluminium content (< 80 at.%). The alloys were produced by conventional casting (ingots) and melt-spinning (ribbons). Structural characterization was carried out for bulk ingots first, and then for the melt-spun ribbons. The ingots possessed a multiphase crystalline structure, as confirmed by X-ray diffraction and scanning electron microscopy observations. The amorphous structure of the melt-spun ribbons was determined by X-ray diffraction and transmission electron microscopy. SEM observations and EDX element maps of the cross-section of melt-spun ribbons indicated a homogeneous elemental composition. Neutron diffraction revealed the presence of nanocrystals in the amorphous matrix of the melt-spun ribbons. DSC data of the melt-spun ribbons showed exothermic events corresponding to the first crystallization at temperatures of 408 °C and 387 °C for Al79Ni5Fe5Y11 and Al79Ni11Fe5Y5, respectively.