X-ray-absorption fine structure (XAFS) and x-ray-diffraction (XRD) measurements of disordered alloys Au{sub x}Cu{sub 1-x} and Au{sub 0.5}Ag{sub 0.5} prepared by melt spinning were performed. In the Au{sub 0.5}Ag{sub 0.5} alloy, no significant local deviations of the atoms from the average fcc lattice were detected while in Au{sub x}Cu{sub 1-x} alloys, significant deviations of atoms from the average fcc lattice were found. Mean-square vibrations of the Cu-Cu distances revealed by the XAFS in Au{sub x}Cu{sub 1-x} alloys indicate the weakening of contact between Cu atoms in the dilute limit. Our computer simulation for Au{sub x}Cu{sub 1-x} clusters of 10{sup 5} atoms reproduces the main features of both the XAFS and XRD data.

A correlation between precise x-ray powder diffraction patterns and atomic size mismatch in disordered mixed crystals (alloys and ionic crystals) is observed. The anisotropy of the elastic moduli has been taken into account for evaluation of the strain energy density of the mixed crystals revealed in x-ray powder diffraction measurements. The precursor of the phase transformation for a quenched disordered Au-Cu alloy is identified.

The technique of magnetic pulse compression (MRC) is widely used in numerous applications like high energy pulse lasers, electron beam accelerators, pulse sources for X-rays tubes etc.

High-frequency properties of toroid cores made of amorphous glass-coated micro-wire are reported in this work. The frequency dependencies of permeability and loss factor in the 0.1–30 MHz range are presented. We studied also the dependence of specific losses on flux density. The real part of effective permeability lies in the range of 150–1000, and the value is nearly constant in a broad frequency range (up to 30 MHz). The imaginary part demonstrates a monotonous increase up to 30 MHz for all samples. Specific losses of micro-wire cores are small in comparison to those of ferrite cores.

Static and high-frequency 1–30 MHz properties of the (Co100−xMnx)75B15Si10 microwires cast using the modified Taylor’s technique are reported. The hysteresis loop and the frequency dependence of permeability indicate that the longitudinal magnetization process occurs by coherent rotation of the moments. The values of static permeability are in good agreement with those predicted by the theory of ferromagnetic resonance where damping is taken into account. We observed a close correlation between the static permeability and the high-frequency limit (the frequency up to which the real part of permeability is still constant). For glass-coated CoMn microwires, this limit is considerably higher than that given by the Snoek equation.

Disordered alloys Au x Cu 1-x prepared by melt spinning method were analyzed by XAFS taken at 80 K. Local atomic structure around Au and Cu atoms was measured and strong deviations from perfect fcc structure were obtained resulting from the size disparity between Au and Cu atoms. A sharp asymmetry was found between the shorter (Cu-Cu) and the longer (Au-Au) nearest neighbor bond lengths. Average first nearest neighbor distance was found greater than obtained using linear interpolation of the pure components. Results on Debye-Waller factors showed strong concentration dependence for the Cu-Cu bond, suggesting the loosening of contact between these atoms when the concentration of Au increases.

X-ray-absorption fine-structure (XAFS) measurements of metallic glass Al0.91La0.09 and a crystalline phase Al11La3 formed by annealing of the glass were made at the La L(3) edge and analyzed by the splice method. The first-neighbor partial radial distribution functions about the La atoms for the crystal and glass were obtained at T=12 K demonstrating the difference between their local structures. The shortest La-Al distance (mean value 3.09+/-0.05 Angstrom) within the glass was distinctively smaller than within the crystal Al11La3 (3.21+/-0.05 Angstrom). This partial shortening of the La-Al bonds decreases the size mismatch between the La and Al atoms making the glass formation more favorable with anomalously low content of La during the quench. Monte Carlo simulations were performed for the Al-La glass and agreement with the XAFS result was obtained.

X-ray-absorption fine-structure ~XAFS! measurements of metallic glass Al 0.91La0.09 and a crystalline phase Al 11La3 formed by annealing of the glass were made at the La L3 edge and analyzed by the splice method. The first-neighbor partial radial distribution functions about the La atoms for the crystal and glass were obtained at T512 K demonstrating the difference between their local structures. The shortest La-Al distance ~mean value 3.0960.05 Å! within the glass was distinctively smaller than within the crystal Al 11La3 (3.2160.05 Å!. This partial shortening of the La-Al bonds decreases the size mismatch between the La and Al atoms making the glass formation more favorable with anomalously low content of La during the quench. Monte Carlo simulations were performed for the Al-La glass and agreement with the XAFS result was obtained. @S0163-1829 ~96!08826-1#

XAFS data of metallic glass Al0.91La0.09 and a crystalline phase Al11La3 formed by annealing of the glass were measured at the La L3 edge at T = 12 K and analyzed using the radial distribution function method. The shortest LaAl distance appeared to be distinctively smaller within the glass than in the crystal. This difference decreases the disparity in size of La and Al in the alloy, allowing their mixing in the glassy state.

The effect of the initial melt temperature on the structure and properties of amorphous alloys was studied. It has been assumed that this effect is determined by the microscopically heterogeneous structure of the melts as well as by the irreversible changes in the structure with sufficient overheating of the melts. Our new approach allows us to extend significantly the possibilities of preparation of new amorphous alloys by melt temperature regulation before rapid quenching.In this paper the proposed approach has been applied to the preparation of new aluminium-based high ductility alloys. Experimental investigation of the viscosity and surface tension of Al91La5Ni4 and Al91Ce5Ni, in the liquid state allows us to determine the temperature range suitable for preparation of these alloys in the amorphous state. The effect of the initial melt temperature on the electrical resistivity and crystallization features has been studied.

This paper presents the results of measurements of the isochoric heat capacity of liquid xenon in stable and metastable states. The behaviour of thermodynamic quantities near the boundary of the essential instability is discussed. It is shown that at the spinodal points (with the exception of the critical point) the isochoric heat capacity and the adiabatic compressibility have finite nonzero values. Thus, the incorrectness of the pseudospinodal hypothesis in the theory of phase metastability has been revealed.