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1
Content available Thermodynamic properties of dilute Co-Fe solid solutions studied by 57Fe Mössbauer spectroscopy
Konieczny R., Idczak R.
Nukleonika
|
2017
|
Vol. 62, No. 2
109--115
EN
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.
2
Content available Temperature dependence of the short-range order parameter for Fe0.90Cr0.10 and Fe0.88Cr0.12 alloys
Idczak R., Konieczny R.
Nukleonika
|
2015
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Vol. 60, No. 1
35--38
EN
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.
3
Content available Mean hyperfine fields at 57Fe in dilute iron-based alloys studied by Mössbauer spectroscopy
Idczak R., Konieczny R., Chojcan J.
Nukleonika
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2015
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Vol. 60, No. 1
39--42
EN
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 hyperfi ne magnetic fi eld 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.
4
Content available Interactions between osmium atoms dissolved in iron observed by the 57Fe Mössbauer spectroscopy
Konieczny R., Idczak R., Chojcan J.
Nukleonika
|
2015
|
Vol. 60, No. 1
75--79
EN
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 fi ndings are in qualitative agreement with the Miedema’s model predictions.
5
Content available Atomic short-range order in mechanically synthesized iron based Fe-Zn alloys studied by 57Fe Mössbauer spectroscopy
Konieczny R., Idczak R.
Nukleonika
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2015
|
Vol. 60, No. 1
69--73
EN
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 fi rst 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.
6
Content available Thermodynamic properties of Au-Fe alloys studied with 57Fe Mössbauer spectroscopy
Idczak R., Konieczny R., Chojcan J.
Nukleonika
|
2013
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Vol. 58, No. 1
93-97
EN
The room temperature Mossbauer spectra of 57Fe were measured for Au1.xFex alloys with x in the range 0.01 less-than or equal to x less-than or equal to 0.03. The obtained data were analysed in terms of short range order parameter (SRO) and the binding energy Eb between two iron atoms in the studied materials using the extended Hrynkiewicz-Krolas idea. The estimated negative SRO parameters and the positive binding energy suggest ordering tendencies in Au-Fe alloys at low iron concentration. The extrapolated value of Eb for x = 0 was used for the computation of enthalpy of the solution of Fe in Au. The results were compared with the corresponding data derived from calorimetric measurements, previous Mossbauer experiments and resulting from the cellular atomic model of alloys by Miedema.
7
Content available Positron annihilation in precious and common opals
Chojcan J., Sachanbiński M., Idczak R., Konieczny R.
Nukleonika
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2013
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Vol. 58, No. 1
225-228
EN
The nano-porosity structure of several non-crystalline opal samples of different origin was investigated with positronium atoms. The obtained data show that the structure depends on both the kind of opal (precious, common or hyalite) as well as the place of its creation (sedimentary or volcanic rocks). The sizes of the pores "seen" by positronium atoms are relatively small, not greater than about 1 nm for all studied samples which may suggest that the pores are located inside the silica matter from which the samples are made. Moreover, the pores detected in the "sedimentary" precious opals are smaller and have less diverse sizes than those found in 'sedimentary" common opals and "volcanic' precious opals.
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