Metal Science and Heat Treatment

Ivanov, A.; Klimanek, P.; Polyakov, A.

doi: 10.1007/BF02471304pmid: N/A

1. We have analyzed the substructure from the intensity of x-ray reflections using the traditional (mosaic crystal) and the suggested (random distribution of dislocations) extinction models. The results of the x-ray analysis coincided statisfactorily with the data of the microscopic study. 2. We have given a description of the statistical theory of dynamic scattering of x-rays from actual crystals as applied to a study of the dislocation structure. 3. We have described a method for analyzing the parameters of the substructure from the profile of one x-ray line and presented the results of such an analysis which happen to be in good agreement with the data of traditional analysis by two lines and with the measured results obtained by other methods.

Ivanov, A.; Yagodkin, Yu.

doi: 10.1007/BF02471305pmid: N/A

Diffraction methods of analysis can be used for controlling materials in the production of various parts. As compared to traditional control techniques these methods are nondestructive and quite rapid.

Shelekhov, E.; Sviridova, T.

doi: 10.1007/BF02471306pmid: N/A

The developed set of programs realizes standard and original methods for processing polycrystalline spectra, namely, qualitative and quantitative phase analysis, determination of the parameters of the fine crystalline structure and macrostresses, and determination of the crystal structure by a diffractogram of a polycrystal. The use of these programs simplifies considerably and accelerates the performance of structural research.

Yagodkin, Yu.; Lileev, A.; Menushenkov, V.; Skakov, Yu.

doi: 10.1007/BF02471307pmid: N/A

1. We have analyzed the results of x-ray diffraction studies of the phase composition, the texture, and the special features of the fine crystalline structure of magnetic materials based on SmCo5 and Nd2Fe14B compounds. The structural characteristics are shown to be related to the properties of the alloys. 2. The suggested methods of study can be used for controlling the quality of alloys for permanent magnets including under industrial conditions.

Somenkov, V.; Glazkov, V.; Shil'shtein, S.; Zhukov, V.; Bezmel'nitsyn, V.; Kurbakov, A.

doi: 10.1007/BF02471308pmid: N/A

Synthesized C60F48 fluoride and C60D8, C60D18 and C60D36 deuterides of fullerene C60 are described. All the compounds have a f.c.c. structure (like the original C60) with periodsa=1.726, 1.423, 1.448, and 1.498 nm, respectively. Powder neutron diffraction diagrams are described on the basis of a double-shell model, i.e., an internal carbon sphere with a radius of 0.356 nm and a fluorine or deuterium sphere with a radius of 0.530 or 0.470 nm, respectively. The structure of the fluorinated and deuterated fullerenes is discussed with allowance for the existence of covalent bonds between the shells inside the molecule and van der Waals bonds between the peripheral atoms of one molecule and neighbor molecules. The description of the structure of the fullerene derivatives is based on the assumption that deuterium or fluorine atoms are absent on the external shell in the places of contact with the neighbor molecule. The low-temperature behavior of the C60F48 and C60D36 compounds is studied. A phase transformation in the C60F48 fluoride atT=270 K is described, which is similar to the transformation of an orientation type in isostructural fullerene C60 at a close temperature. The observed changes in the intensities of the diffraction peaks are described under the assumption that the phase transformation is accompanied by a decrease in the volume at invariable radii of the carbon and fluorine spheres. Similar changes in the intensity have been determined in the C60D36 compound.

D'yakonova, N.; Sviridova, T.; Skakov, Yu.; Shelekhov, E.

doi: 10.1007/BF02471309pmid: N/A

1. The change in the crystal structure of the studied intermetallic compounds observed under different extreme actions (quenching from liquid state, ion irradiation, treatment in a ball mill) can be described as a change in the packing of close-packed layers (the formation of packing defects and polytypes in μ-, λ-, and ε-phases) or a change in the atomic ordering (ε, σ, Cr3Si type, andH-phase). 2. The relative stability of the crystalline state of intermetallic phases under high-energy actions is independent of the type of the action and is determined by the crystallochemical nature of the phase.

Khmelevskaya, V.; Malynkin, V.

doi: 10.1007/BF02471310pmid: N/A

1. In many metallic materials irradiated in a narrow range of parameters (dose, temperature, intensity) the structure undergoes changes characterized by the formation of a heterophase pattern in the earlier single-phase and equilibrium material, the presence of small clusters in the microstructure, a considerable change in the properties (microhardness, temperature dependence of the thermo-e.m.f.), and their nonmonotonic dependence on the irradiation parameters. 2. We suppose (and the supposition has been confirmed by the results of a computer simulation of local restructuring of the crystal lattice) that the observed changes in the structure are caused by the formation of atomic groups (clusters) with a symmetry differing from that of the matrix.