Advanced Materials Research Vol. 1013

Abstract: The evolution of the dislocation structure and the ensemble of boundaries during plastic deformation of Zr-Nb alloys studied using electron microscope. The role of the anisotropy of slip in the formation and restructuring of the boundaries, recurrence of dislocation transformation was established. Special emphasis is placed on specific features of geometrically necessary defects evolution. It was found that the geometrically necessary boundaries formation involves an athermal coalescence as a mechanism of relaxation of large accumulated internal stresses, which prevents fracture in an anisotropic polycrystalline material.

Abstract: In the paper on a base of electron microscopy study a dynamic of evolution of dislocation substructures (DSS) arising on a stage large plastic deformation is examined. Microband dislocation substructure is a foundation of this consideration. Formation and evolution at deformation of this substructure for Cu-Al and Cu-Mn alloys are considered.

Abstract: The excess density of dislocations and internal stresses in local places of all polycrystal grain are determined. In work the methods of bending extinction contours observed by TEM is used to determine internal stresses of the deformed material. Thus depending on the deformation nature in each case components of elastic and plastic deformations or only plastic deformation was considered. The paper discusses the results of distribution of excess dislocation density and internal stresses within the grains of the austenitic steel deformed by tension (ε = 25%).

Abstract: In the present study, the features of plastic strain localization and structure of polycrystalline low carbon steel Fe-0.07%C were investigated after hot rolling and electrolytic hydrogen saturation. The method of double-exposure speckle photographyhave been used for identification of main types and parameters of plastic flow localization at different stages of strain hardening.Shown the effect of hydrogen on changing of defect substructure and cementite morphology by using optical and electron microscopy.

Abstract: This work presents the results of experimental investigations into deformation relief formed at the faces of aluminium single crystals. The aim of the investigations was to define the rules of macro fragmentation and macro localisation processes in plastic deformation. It was established that for the families of maximum loaded planes {111} in the aluminium single crystals, one can differentiate volumes which aren't limited to the specimen's front face. It is assumed that shearing in these volumes is eased during plastic deformation due to the absence of a reverse stress. Moreover, it is suggested that such volumes are called volumes of eased slip (VES). In addition to this, the role played by the volume of eased slip at the macroscopic level during the plastic deformation process was examined.

Abstract: By X-ray diffraction and scanning electron microscopy using the method of back-scattered electrons the parameters of the solid solution (the lattice parameter and the mean-square displacement of atoms) and the grain boundary ensembles in the alloy Pd₃Fe with the superstructure L1₂ have been investigated depending on the degree of the long-range atomic order. The relationship between the proportion of the twins Σ3 in the spectrum of special boundaries and the mean-square displacement of atoms was detected.

Abstract: Phase composition and γ′-phase morphology of a superalloy on based N I-Al doped by high-melting elements in it after ordering annealing hawe been studied by TEM, SEM and electron microdiffraction methods. It is revealed that after annealing superalloy comprises mainly γ′-phase (∼90%). The structure, distribution and morphology of γ′-phase is determined.

Abstract: The paper presents results of the Rietveld refinement method in X-ray diffraction quantitative phase analysis of calcium mono-aluminate, the mineral. It has been stated that the theoretical calcium mono-aluminate CaO⋅Al₂O₃. is a high-stable phase, mixing energy of which is equal to 16214,10 eV. Ab-initio calculations and Rietveld refinement method were used to identify die structural state of CaO⋅Al₂O₃.

Abstract: The results of X-ray and thermodynamic analysis of the phase formation in the system Zr-YO, which is the starting material for the formation of yttrium-stabilized ceramic zirconia. Found that the material is multiphase and contains monoclinic, cubic and tetragonal zirconia weight ratios which vary considerably.

Abstract: The paper presents neutron diffraction analysis and X-ray investigation of ordered alloys Ni₃(Mn,Ti) within the concentration range from 0 to 12.5 at.% Ti. The significant effect of the third alloying element Ti on the atomic long-range order was observed in superstructure L1₂ of alloy Ni₃Mn. Experimental study has showed that a rapid quenching in ice water does not provide disordered Ni₃(Mn,Ti) alloys. The two-phase region of internmetallic bonds was detected in compounds L1₂ and D0₂₄. The paper presents results estimation of electrical resistivity, normal and abnormal values of hall coefficient, Nernst–Ettingshausen effect, thermal electromotive force, and average atomic magnetic moment in quenched and annealed Ni₃(Mn,Ti) alloys. Positive values of abnormal hall coefficient and Nernst–Ettingshausen effect were detected that confirms the predominant contribution of antiparallel spin 3d holes in conductivity. It is shown that in 2.2 at.% annealed Ti alloys ordering promotes 3d electron localization.