A Method for the Spectroscopic Diagnostic of the Peculiarities of Materials Using the Semi-Auger Effect

We investigated the low energy satellites in the Rontgen spectra using the many-particle theory. These satellites are results of the radiative semi-Auger decay of the inner vacancy states. We did not treat only ordinary radiative decay. There exist the excitations of one of the atomic electrons together with the photon emission. We presented results of radiative semi-Auger decays of vacancy states in Ar atom. The knowledge of these processes is important for understanding the same processes in the case of the nanoparticles (molecules, fullerenes, clusters). Research in the field of the new materials requires more sophisticating methods which will open the new possibilities for obtaining materials of particular design, too. The theory which is presented in the paper may be easily generalized in case of particles like fullerenes and clusters.10th Annual Conference of the Materials-Research-Society-of-Serbia, Sep 08-12, 2008, Herceg Novi, Montenegr

The study of relaxational properties and crystallization of the metallic glass Fe80Si10B10

The three-component amorphous alloy Fe80Si10B10 was prepared on the surface of copper roller by rapid quenching in the vicinity of the eutectic point. Changes of the obtained spin-glass metastable phase were investigated by differential scanning calorimetric analysis (DSC), as a function of the relaxation temperature, and by X-ray diffraction (XRD) measurements, in the crystallization phase of the metallic glass. The crystallization kinetics and the corresponding activation energies, E(a), were determined using the dynamic thermal treatment. For the study of the crystallization process, the XRD measurements were done before and after crystallization. On the basis of these data, the products of the investigated metallic glass crystallization have been determined, The Curie temperature of the ferromagnetic transition has been determined from the DSC measurements in the low temperature region. The Johnson-Melh-Avrami dynamic model for nun-isothermal conditions, and the DSC measurements were used for determination and definition of the parameter n, responsible for the mechanism of crystallization, whereas the Vogel-Fulcher model for isothermal conditions and the DSC measurements were used to determine the characteristic time of crystallization, tau(t). The obtained results for E(a), n and tau(t) are in good agreement with other authors results

Determination of the activation energy of nucleation and grain growth in Ni-P metallic glass

Using DSC, we have studied the crystallization kinetics of Ni-P metallic glasses By the Transmission electron microscopy (TEM) image, we have determined the condition of early nucleation saturation in the NI-P crystallization processes and from this the growth activation energy has be determined. According to the Arrhenius equation, the apparent activation energy in the small transformation range can be calculated. By extrapolation we have obtained the activation energy for nucleation (E-n) and growth (E-g). Based on this, the change relation between proportions of nucleation, growth in crystallization and various transformation fraction has been calculated.Trends in Advanced Materials and Processes, 3rd Yugoslov-Materials-Research-Society Conference, Sep 20-24, 1999, Herceg Novi, Yugoslavi

Determination of activation energy spectrum for Fe40Ni40B20 metallic glasses

Very inherent metastable character of amorphous metal alloys, induces structure phase transformations which manifest themselves in thermally activated relaxation processes. The kinetics of these processes can be interpreted with the aid of two models: two equilibrium states and spectrum of activation energies. Structure relaxation of amorphous Fe40Ni40B20 metallic glass has been observed by measuring changes in electrical resistivity at corresponding isothermal treatments. Electrical resistance changes have been measured at liquid nitrogen temperature (78 K) using the d.c. method and a fixed probe. By measuring the resistivity change during isothermal treatment, logarithmic kinetics has been observed. Also, Q(E) function has been derived having a symmetric distribution around the value of activation energy of 2.1 eV, determined by some other methods too.Advanced Materials and Processes, 2nd Yugoslav Conference on Advanced Materials (YUGOMAT II), Sep 15-19, 1997, Herceg Novi, Yugoslavi

Many-body calculations of dynamic polarizability, reffractive index and verdet coefficient

Within the framework of the many-body theory by using the Random Phase Approximation with Exchange (RPAE) method we calculated the frequency dependent polarizability, refractive index, and Verdet coefficient of some atoms. Calculated time-dependent peculiarities of a set of atoms are very significant in the nano-region and might be important for designing new materials.Recent Developments in Advanced Materials and Processes, 7th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS), Sep 12-16, 2005, Herceg Novi, Montenegr

Crystallization kinetics of Fe-B based amorphous alloys studied in situ by X-ray diffraction and differential scanning calorimetry

Crystallization processes for the amorphous metallic alloys Fe-Si-B-Ni and Fe-B-Zr-Cu were investigated, in-situ during Joule-heating by X-rays diffraction technique With simultaneous monitoring of the electrical resistance. We determined the main Structural transitions and crystalline phases formed during heating, and correlated these results to the observed resistance variations. With increasing annealing current, the resistance initially decreased due to stress relaxation, followed by a drop to a minimum value due to massive nucleation and growth of alpha-Fe nannocrystals. Further annealing causes the formation of small fractions of Fe-B, B2Zr or ZrO2, while the resistance increased due to temperature enhancement. In-situ XRD measurements allowed the identification of metastable phases, as the gamma-Fe phase which Occurs at high temperatures. Exothermal peaks observed in the differential scanning calorimetry (DSC) for each alloy corroborate the finings. We also have performed DSC measurements at several heating rates, which allowed determination of the Avrami exponent and crystallization activation energy for each alloy. The obtained activation energies (362 and 301 kJ/mol for Fe-B-Zr-Cu; 323 kJ/mol for Fe-Si-B-Ni) are comparable to the reported values for amorphous iron alloys, while the Avrami exponent values (n = 1.0 or n = 1.2) are consistent with diffusion controlled crystallization processes with nucleation rates close to zero.Progress in Advanced Materials and Processes, 5th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS 2003), Sep 15-19, 2003, Herceg Novi, Yugoslavi

Many-body calculations of dynamic polarizability, reffractive index and verdet coefficient

Within the framework of the many-body theory by using the Random Phase Approximation with Exchange (RPAE) method we calculated the frequency dependent polarizability, refractive index, and Verdet coefficient of some atoms. Calculated time-dependent peculiarities of a set of atoms are very significant in the nano-region and might be important for designing new materials.Recent Developments in Advanced Materials and Processes, 7th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS), Sep 12-16, 2005, Herceg Novi, Montenegr

The study of crystallization processes of TiNi ribbon

By liquid quenching technique, for instance, alloys of early transition metals (Zr, Nb, Ti, Ta) and late transition metals (Fe, Co, Ni, Cu, Pd) can be quenched rapidly from the melt to form glasses. These systems form glasses of near deep eutectic composition. Various amorphous alloys can be formed from Ti-Ni. In this study, the synthesis of rapidly solidified Ti-27%Ni alloy was conducted by melt spinning technique. Differential scanning calorimetry (DSC) measurements were made using a Perkin-Elmer DSC-2C under flowing argon, in the interval 323-873 K. Crystallization temperatures T-x of 761.26 K, 773.42 K, and 782.72 K, were obtained at heating rates 10 K/min, 25 K/min, 40 K/min respectively. The XRD patterns were obtained using a Rigaku D/max-IIB, X-ray diffractometer with Cu K-alpha radiation.Advanced Materials and Processes, 2nd Yugoslav Conference on Advanced Materials (YUGOMAT II), Sep 15-19, 1997, Herceg Novi, Yugoslavi

Fitting the glow curve and calculating TL parameters

A new glow curve fitting method using the Gauss-Lorentz asymmetric function is suggested. By calculating the thermoluminescence (TL) parameters it is shown that this is compatible with a general-order kinetics model. The relations between TL parameters and fitting function parameters are determined. The new fitting method is tested by computer simulated glow curves. The coefficients of Chens interpolation-extrapolation formula for calculation of TL parameters are presented in an analytical form. It is shown that the Chen method is a special case of the integral method of TL parameter calculation

On the stability and structure of Zr-Cu and Zr-Ti-Cu alloys

The alloys Zr-Cu-Ti and Zr-Cu have been prepared by melt-spinning and mechanical alloying techniques. Their thermal behaviour and structure factors have been investigated. Thermal properties obtained by differential scanning calorimetry, of an amorphous alloy (54Zr34Cu10Ti), were tested in argon and nitrogen atmospheres. It was shown that crystallization (devitrification) proceeds through five different stages within the temperature range 565 to 976 K. Particular attention is paid to a discussion of the crystallization process of each stage in correlation with the results obtained by X-ray analysis