Advanced Materials Research Vol. 1013

Abstract: The paper presents a formation of residual stresses near the weld-affected zone. It is shown that the residual stress values depend on load application and the type of weld joints. The proprietary know-how is suggested for the analysis of stress and strain state using measurement of the ultrasound velocity in weld joints under load. A correlation between effective and residual stresses is shown when testing the bridge crossing over the river Tom (Tomsk, Russia). A method of reducing these stresses using the ultrasonic impact treatment is suggested herein.

Abstract: Results of research of mechanical properties of calciumphosphate coatings produced by the method radio frequency magnetron sputtering on bioinert alloys of titanium, zirconium and were presented. Calcium phosphate coatings show high value of adhesion strength to bioinert metal surface. Calcium phosphate coating on titanium-niobium alloy surface shows the highest value of adhesion strength. Mechanical properties of a composite material based on bioinert alloy and calcium phosphate coating are higher than properties of the components of composite material separately.

Abstract: Studies on the structure and the phase composition of the deposited material were carried out using methods of X-ray structure analysis and electron diffraction microscopy of extract coal replicas and thin foils on steel Hardox 400. Formation of a multiphase state, represented by grains of α-iron and inclusions of carbide phases based on iron, chromium, and niobium, is revealed.

Abstract: TEM research of the structure of multilayered coatings consisting of alternating layers Si-Al-N and Zr-Y-O of equal thickness was carried out. It was shown that boundaries between different layers were the sharp enough, and the chemical composition in each layer was homogeneous. The phase composition of the layers on the basis of Zr-Y-O contained basically nanocrystalline ZrO₂ and the layers on the basis of Si-Al-N, contained partially amorphous, and partially nanocrystalline Si₃N₄.

Abstract: The influence of temperature fields and different reactive media on the structure and morphology of small icosahedral particles (ISPs) are investigated. It is shown experimentally that ISPs of micron size can be transformed into advanced functional materials with a developed surface. The leading role of disclination defects for the transformations occurring in ISPs is established. Potential fields of application of the new functional materials based on transformed ISPs are discussed.

Abstract: A number of nonequilibrium nanocrystalline fcc solid solutions Cu_1-x-Ag_x (x = 0,1; 0,2; ... 0,9; 1,0) were obtained by mechanical alloying of powders by the use of high pressure torsion. Chemical homogeneity, microstructure, mechanical properties and thermostability were studied. The obtained alloys were found to be characterized by a positive excess over Vegard law, ~ 20 nm grain sizes, a microhardeness of 4.5-6 times higher than the Cu and Ag one and brittle type of the fracture surface. In situ shear stress vs. strain measurements and energy-power parameters estimation were performed. A decomposition of nonequilibrium solid solution induced by a thermal influence begins from close to room temperatures and finishes completely at heating up to 500°С accompanied by collective recrystallization development.

Abstract: Influence of a nearly room and cryogenic severe deformation of a Cu-Zn powder mixture on a structural and phase transitions and kinetics of mechanical alloying was investigated. A sufficient retardation of structural and phase transformations and low homogeneity of solid solution made at 80K were established in comparison to processing at 273K. A lowering of solution formation kinetics rate is supposed to be due to lock of plastic deformation mechanisms, activated by thermal impact.

Abstract: The studies of the structure and tribological properties of the surface layer of copper-doped carbon was performed. The formation of an island structure with a low coefficient of friction (relative to the original copper) was detected.

Abstract: The doping of the surface layer of titanium by the yttrium, oxygen and carbon was implemented. Irradiation of the doped layer by intense electron beam leads to the formation of the multiphase structure and the nanosubmicron range having a high microhardness (at 3-fold higher than the hardness of the original structure) and a low coefficient of friction (6 times lower than the friction coefficient of the starting material).

Abstract: An atomic model is proposed which describes the formation of dislocations and deformation twins through a direct plus reverse martensitic transformation localized in two or several slip planes. The reasons and mechanisms for the formation of partial dislocations and mechanical twinning in nanocrystals under plastic deformation are discussed.