Advanced Materials Research Vol. 1085

Abstract: The results of investigation of the structure, physical and mechanical properties of the Ti-Nb alloy ingots with different composition obtained by arc melting are presented. X-ray diffraction and microstructural analyses were used. Microhardness was measured and the Young’s modulus of the alloys was evaluated. When the content of niobium in the alloy changes from 10 to 40 mass.%, phase composition of the alloy varies from α-and α'-phase (10 mass.% of Nb) to α'-, α''- and β-phases (25 mass.% of Nb), to the β-phase (40 mass.% of Nb). The alloy containing 40 mass.% Nb has the lowest Young’s modulus.

Abstract: Ceramics samples in the form of a parallelepiped with high strength characteristics have been made. For the manufacture of the ceramics samples a powder mixture from submicron В4С powder with additives (1 wt%, 5 wt%, 10 wt%) of boron carbide nanopowder was used. The physical properties of the powder mixtures and strength properties of sintered ceramics have been studied. It was shown that the use of submicron fractions of the boron carbide powder together with nanoadditives is a determining factor in the formation of dense fine-grained structure providing improved physical and mechanical properties of the ceramics.

Abstract: The paper assessed the possibility of using acoustic emission from the dielectric sample during stepwise loading. The electromagnetic signal from the sample was detected by using an apparatus of mechanical repeatedly pulsed excitation of the sample at each stage of loading. It was found that the response consists of a deterministic component (due to the excitation pulse) and random components noise and acoustic emission. It were allocated random components, calculated their standard deviations. The influence of the electromagnetic emission on standard deviation of the random component of response under step load on the specimen was evaluated. It has been shown that the component of the electromagnetic emission can be an informative parameter to evaluate defectiveness of the object of a dielectric material under load.

Abstract: In this article, we analyzed connection between development of grain misorientation of different olivine fabrics from dunites of the Tarlashkinsk Massif (SE Tuva, Central Sibiria) and their geometrical parameters (grain size, specific area of grain boundaries, volume fraction of large and small components). Crystallographic orientation of olivine fabric types was also analyzed. It was indicated that bimodality in grain sizes disappears while changing into mosaic type. It was obtained by the EBSD method that the grain orientation changes starting with porphyroclastic type, and maximum scattering of olivine grain misorientations is observed when forming mosaic fabric. The results obtained confirm a hypothesis stipulated by authors earlier about deformation transformations of olivine as a result of geological processes during the obduction of mantle ultrabasites.

Abstract: Compositional and structural features of peat allow creating efficient additives for cement systems by means of the various processing methods. The basic selection criteria of the method of production are feedstock composition and required properties of the product. This paper presents outcomes of research of thermal and chemical conversion of peat and influence of processing method on the properties of the obtained substance.

Abstract: This paper is devoted to the defect structure study of commercially pure titanium after hydrogen sorption-desorption cycles by means of positron lifetime (PL) and Doppler broadening spectrometry. Material was loaded with hydrogen from the gas phase till the concentration of hydrogen reached the value of 0.05 wt.% for each cycle. The essential changes in the positron annihilation characteristics of the sample are occurred after the each stage of treatment.

Abstract: This paper presents experimental results of eddy current analysis of hydrogen in technically pure titanium alloy. Eddy currents when penetrating various depths change their parameters in relation to material properties. Each layer possesses different degree of hydrogenation and differs in number of defects and their location. The measurement of hydrogenated titanium conductivity in various depths with different angular position of eddy current probe were performed and discussed. Components` surface measurements caused by hydrogenation were registered by currents with the frequency of 10 MHz. The results can be used for the development of new materials with required properties.

Abstract: Plastic strain localization patterns in compression-strained alkali halide (NaCl, KCl, and LiF) crystals have been studied using a double-exposure speckle photography technique. The main parameters of strain localization autowaves at the linear stages of deformation hardening in alkali halide crystals have been determined. A quantitative relationship between the macroscopic parameters of plastic flow localization and microscopic parameters of strained alkali halide crystals has been established.

Abstract: Thermokinetic constants for the drying process of different steppe fuels are determined using the developed method for solving inverse kinetic problems on the basis of obtained experimental data. The anatomical structure of the investigated fuels is found to be a dominant parameter influencing on evaporation. The basic conductor of combustion is proposed for prediction of fire hazard for the investigated area.

Abstract: Strain-induced folds on the lateral faces of copper monocrystals generated in compression and sliding tests have been studied using SEM and OM techniques. It has been established that these folds form at different structural scale levels by similar mechanisms related basically to distortion of faces in the vicinity of their end faces during the so-called "lip" formation. Under compression folds have also been formed on the lateral areas bended and on the strain domain boundaries.Keywords: single crystal, wrinkling, folding fragmentation, texture, sliding.