Atomic short-range order in mechanically synthesized iron based Fe-Zn alloys studied by 57Fe Mössbauer spectroscopy

Mechanical alloying method was applied to prepare nanocrystalline iron-based Fe1−xZnx solid solutions with x in the range 0.01 ≤ x ≤ 0.05. The structural properties of the materials were investigated with the Mössbauer spectroscopy by measuring the room temperature spectra of 57Fe for as-obtained and annealed samples. The spectra were analyzed in terms of parameters of their components related to unlike surroundings of the iron probes, determined by different numbers of zinc atoms existing in the neighborhood of iron atoms. The obtained results gave clear evidence that after annealing process, the distribution of impurity atoms in the first coordination spheres of 57Fe nuclei is not random and it cannot be described by binomial distribution. The estimated, positive values of the short-range order parameters suggest clustering tendencies of Zn atoms in the Fe-Zn alloys with low zinc concentration. The results were compared with corresponding data derived from Calphad calculation and resulting from the cellular atomic model of alloys by Miedema

Influence of non-polymeric substances localized in the amorphous phase on selected properties of semicrystalline polymers

Semicrystalline polymers are chemically/physically inhomogeneous, since they contain from as little as a fraction of a percent to even a few percent of non-polymeric substances (oligomers, antioxidants, processing agents) of different physicochemical properties, preferentially localized in non-crystalline regions. In this paper, the extraction process of non-polymeric substances with the use of supercritical CO2 for several semicrystalline polymers, such as polypropylene, high and low density polyethylene was performed. The quantitative/semi-qualitative analysis of extracted substances was performed and their thermal properties were determined. Then, their influence on the structure of amorphous phase-content and size of free volume pores were assessed. Finally, the influence of non-polymeric substances on thermal, thermo-mechanical and barrier properties of analyzed polymers and the course and intensity of the cavitation phenomenon during uniaxial stretching was determined

Thermodynamic properties of dilute Co-Fe solid solutions studied by 57Fe Mössbauer spectroscopy

The Co1-xFex alloys where x ranges from 0.01 to 0.06 were measured at room temperature using transmission Mössbauer spectroscopy (TMS). The analysis of the obtained data allowed the determination of the short-range order (SRO), the binding energy Eb between two iron atoms in the studied materials using the extended Hrynkiewicz-Królas idea and the enthalpy of solution HCo-Fe of Fe in Co. The results showed that the Fe atoms dissolved in a Co matrix interact repulsively and the estimated value of HCo-Fe = -0.166(33) eV/atom. Finally, values of the enthalpy of solution were used to predict the enthalpy of mixing for the Co-Fe system. These findings were compared with corresponding data given in the literature, which were derived from calorimetric experiments and from the cellular atomic model of alloys described by Miedema

Temperature dependence of the short-range order parameter for Fe0.90Cr0.10 and Fe0.88Cr0.12 alloys

The 57Fe Mössbauer spectra for the iron-based solid solutions Fe0.90Cr0.10 and Fe0.88Cr0.12 were measured at different temperatures ranging from 300 K to 900 K. Analysis of the obtained spectra shows that the distribution of impurity atoms in the two first coordination shells of 57Fe nuclei is not random and it cannot be described by the binomial distribution. Quantitatively, the effects were described in terms of the atomic short-range order (SRO) parameters and the pair-wise interaction energy with the help of a quasi-chemical type formulation introduced by Cohen and Fine. The obtained results reveal strong clustering-type correlations in the studied samples (a predominance of Fe-Fe and Cr-Cr bonds). Moreover, the changes in SRO values observed during thermal processing suggest that the distribution of Cr atoms in an α-iron matrix is strongly temperature dependent

Morphology and properties alterations in cavitating and non-cavitating high density polyethylene

Cavitation phenomenon has been marginalised in the past, although it alters morphology and properties of semicrystalline polymers during their plastic deformation. The formation of cavitational pores are due to the loss of cohesion by the amorphous phase. The research in this paper has been conducted on cavitating and non-cavitating high density polyethylenes with identical microstructure of the crystalline component, however, with modified amorphous phase. The influence of cavitation on selected properties and mechanisms activated during tensile deformation of high density polyethylene has been systematically studied including the alterations of yield stress and yield strain, the strain onset of activation of crystallographic slips and martensitic transformation, the intensity of the lamellae fragmentation, the degree of molecular orientation and the amount of heat generated during deformation

Mean hyperfine fields at 57Fe in dilute iron-based alloys studied by Mössbauer spectroscopy

The room temperature Mössbauer spectra of 57Fe were measured for numerous dilute iron-based alloys Fe1−xDx (D = Al, Co, Cr, Mn, Mo, Ni, Os, Pt, Re, Ru, Ta, Ti, V, W, Zn), annealed at 1270 K for 2 h before the measurements. The spectra were analyzed using the Hesse–Rübartsch method in order to determine the mean hyperfine magnetic field at the 57Fe nuclei as a function of concentration x of the minority component of the alloy. As the binary alloys are one-faze solid solutions of an element D in iron, a linear relationship between and x is observed. The result supports the suggestion that Mössbauer spectroscopy is a useful tool for the study of dissolution of different elements in iron

Interactions between osmium atoms dissolved in iron observed by the 57Fe Mössbauer spectroscopy

The room temperature 57Fe Mössbauer spectra for binary iron-based solid solutions Fe1−xOsx, with x in the range 0.01 ≤ x ≤ 0.05, were analyzed in terms of binding energy Eb between two Os atoms in the Fe-Os system. The extrapolated values of Eb for x = 0 were used for computation of enthalpy of solution of osmium in iron. The result was compared with that resulting from the cellular atomic model of alloys by Miedema. The comparison shows that our findings are in qualitative agreement with the Miedema's model predictions

Superconductivity in high-entropy alloy system containing Th

Abstract Th-containing superconducting high entropy system with the nominal composition (NbTa) $$_{0.67}$$ 0.67 (MoWTh) $$_{0.33}$$ 0.33 was synthesized. Its structural and physical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, specific heat, resistivity and magnetic measurements. Two main phases of alloy were observed: major bcc structure and minor fcc. The experimental results were supported by numerical simulation by the DFT Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA)

<p>Fe₃O₄ Magnetic Nanoparticles Under Static Magnetic Field Improve Osteogenesis via RUNX-2 and Inhibit Osteoclastogenesis by the Induction of Apoptosis</p>

International audiencePurpose: The presented study aimed to investigate the effects of Fe 3O 4 nanoparticles and static magnetic field on osteoblast and osteoclasts’ metabolic activity.Methods: Magnetic nanoparticles were prepared by a wet chemical co-precipitation process and analyzed using X-ray powder diffraction, high-resolution transmission electron microscope (HRTEM), dynamic light scattering (DLS), laser Doppler velocimetry, Raman and the Mössbauer spectroscopy. In vitro experiments were performed using MC3T3, 4B12 and RAW 264.7 cell lines. Cells were cultured in the presence of nanoparticles and with or without exposure to the magnetic field. Proteins were investigated with Western blotting and immunofluorescence and Western blot. Gene expression was analyzed with a quantitative real-time polymerase chain reaction.Results: Obtained particles were in the nano-range (average size around 50 nm) and had a spherical-like morphology. The typical hydrodynamic size was in the range 178– 202 nm and Zeta potential equaled – 9.51 mV. Mössbauer spectrum corresponds to the Fe+3 ions in tetrahedral (A) and Fe+3 and Fe+2 ions in octahedral (B) sites of Fe 3O 4. In vitro study revealed cytocompatibility and anti-inflammatory effects of fabricated nanoparticles. Furthermore, it was shown that nanoparticles combined with magnetic field exposure enhance osteogenic differentiation of MC3T3 cells by upregulation of RUNX-2 activity. Under the same experimental condition, nanoparticles and magnetic field decreased osteoclastogenesis of 4B12 by the induction of apoptosis through the mitochondrial-dependent pathway.Conclusion: Fe 3O 4 nanoparticles together with magnetic field can be applied for the fabrication of novel biomaterials for the treatment of bone disorders related to bone loss in which a balance between bone-forming and resorbing cells is disturb