Effect of friction deformation on the structure and properties of a metastable austenitic chromium-nickel steel

The effect of surface friction deformation on the phase composition, structure, and strength properties of a ribbon produced from a chromium-nickel steel with metastable austenite is studied. It is shown that friction processing intensifies the γ-α transformation, creating favorable conditions for the formation of a highly dispersed structure in a thin surface layer and, thus, increasing the microhardness, the elastic limit, the fatigue stability, and the Bauschinger effect. © 2013 Pleiades Publishing, Ltd

SURFACE FRICTION TREATMENT OF SPRING MATERIALS: FEATURES OF STRUCTURE AND PROPERTIES

The influence of frictional surface deformation on the structural state and properties of spring materials based on Fe and Cu is considered.Рассмотрено влияние фрикционного поверхностного деформирования на структурное состояние и свойства пружинных материалов на основе Fe и Cu

Optimization of the ion-plasma nitriding of structural steel

Mathematical planning was used in order to determine the optimal mode for ion nitriding the structural steel 0.38C-2Cr-2Ni-Mo. This was justified by the requirement to preserve strictly limited functional parameters obtained as a result of diffusion saturation: hardness in the range of 450-650 HV in a layer 0.15-0.40 mm deep. According to of X-ray diffraction analysis in addition to reflections from the matrix phase (alloyed ferrite α-Fe), the reflexes of nitride compounds are recorded, namely, the γ′-phase with a FCC lattice (Fe4N) and the ϵ-phase with a HCP lattice (Fe3N) with a high nitrogen content. An analytical expression in the form of a linear function for the studied optimization parameters (microhardness and depth of nitration) was obtained by implementing factor planning and regression processing of the obtained data. This made it possible to assess the degree and direction of influence of the investigated factors on the optimization parameters under study. © Published under licence by IOP Publishing Ltd

Specific Features of the Structure and Properties of Copper-Nickel Alloy MH19, Obtained by Selective Laser Fusion

Рассмотрены структура и физико-механические свойства трехмерной модели, изготовленной методом селективного лазерного сплавления (СЛС) из порошков медноникелевого сплава МН19. Полученная 3D-модель характеризуется отсутствием характерных признаков кристаллического строения и содержит элементы квазиаморфного состояния, а также отличается от стандартной монолитной заготовки меньшей шероховатостью поверхности, более высокими значениями твердости при сохранении практически аналогичных показателей плотности.The structure and physical and mechanical properties of a three-dimensional object produced by selective laser melting (SLM) from powders of copper-nickel alloy (81Cu–19Ni) are considered. The 3D-object is characterized by the absence of the crystalline structure and contains elements of a quasi-amorphous state. More over, the 3D-model differs from the standard cast workpiece in a smaller surface roughness, higher hardness values while maintaining practically the same density indicators

Kinetics of the disorder→order transformation in the Cu - 47 at.% Pd alloy

On the basis of experimental data obtained with the help of resistometric measurements, kinetic C-curves of the isothermal disorder→order transformation have been constructed and the activation energy of the atomic ordering process in the quenched Cu - 47 at.% Pd alloy has been calculated. Deviations from the data in the literature are explained by differences in the methods of obtaining the initial disordered state of the alloy. © 2013 Springer Science+Business Media New York

The additive technology to obtain a three-dimensional model of the 81Cu-19Ni alloy

This paper is devoted to the selective laser smelting (SLS) method description for the article made of powder of a Cu81-Ni19 copper-nickel alloy and the study of the structure and characteristics of the three-dimensional article made using additive technology. To make a 3D model the copper-nickel alloy powder was produced in our laboratory. The chemical composition, microstructure, density, surface roughness and microhardness of an article made of powders of a Cu81-Ni19 copper-nickel alloy are considered. A comparative analysis of the structure, physical and mechanical properties of a sample obtained by the SLS method and the annealed rolled plate was carried out. The article microstructure is characterized by the absence of a typical signs of a crystalline structure and contains elements of a quasi-amorphous state. At the same time, the obtained material differs from the standard monolith billet with a lower surface roughness and a higher hardness values while maintaining almost the same density indices. © Published under licence by IOP Publishing Ltd

Modulation of NKp30- and NKp46-Mediated Natural Killer Cell Responses by Poxviral Hemagglutinin

Natural killer (NK) cells are an important element in the immune defense against the orthopox family members vaccinia virus (VV) and ectromelia virus (ECTV). NK cells are regulated through inhibitory and activating signaling receptors, the latter involving NKG2D and the natural cytotoxicity receptors (NCR), NKp46, NKp44 and NKp30. Here we report that VV infection results in an upregulation of ligand structures for NKp30 and NKp46 on infected cells, whereas the binding of NKp44 and NKG2D was not significantly affected. Likewise, infection with ectromelia virus (ECTV), the mousepox agent, enhanced binding of NKp30 and, to a lesser extent, NKp46. The hemagglutinin (HA) molecules from VV and ECTV, which are known virulence factors, were identified as novel ligands for NKp30 and NKp46. Using NK cells with selectively silenced NCR expression and NCR-CD3ζ reporter cells, we observed that HA present on the surface of VV-infected cells, or in the form of recombinant soluble protein, was able to block NKp30-triggered activation, whereas it stimulated the activation through NKp46. The net effect of this complex influence on NK cell activity resulted in a decreased NK lysis susceptibility of infected cells at late time points of VV infection when HA was expression was pronounced. We conclude that poxviral HA represents a conserved ligand of NCR, exerting a novel immune escape mechanism through its blocking effect on NKp30-mediated activation at a late stage of infection