Influence of barocryodeformation on the hydrogen concentration and acoustic emission in VT1-0 commercial titanium

The concentration of hydrogen with different binding energies and acoustic emission initiated by indentation in VT1-0 commercial titanium in the initial state and after barocryodeformation are measured. The acoustic parameters are found to correlate with the hydrogen concentration in the material.     

Pulsed plasma-immersion ion implantation of aluminum into VT1-0 titanium

The results from investigating the pulsed plasma-immersion ion implantation of aluminum into VT1-0 titanium are presented. It is shown that variations in the elemental and phase composition of surface layers, their microscopic characteristics, and their mechanical properties as a function of implantation time are not monotonous but follow certain patterns. The possibility of interpreting the obtained data in terms of surface modification by metallic clusters with at least ~100 atoms generated in the gas of metal atoms evaporated from cathode spots is discussed.     

Hydrogen accumulation and distribution during the saturation of a VT1-0 titanium alloy by an electrolytic method and from a gas atmosphere

The accumulation, distribution, and thermally stimulated release of hydrogen in a VT1-0 titanium alloy during electrolytic saturation and gas-phase saturation are studied. After electrolytic saturation, a 0.4-μm-thick surface layer consisting of δ hydrides with a binding energy of 108 kJ/mol forms in the alloy. The hydride dissociation after electrolytic saturation in heating occurs in the temperature range 320–370°C. After saturation from a gas atmosphere, δ hydrides with a binding energy of 102 kJ/mol form throughout the alloy volume. The dissociation of the hydrides formed during gas-phase saturation in heating occurs in the temperature range 520–530°C. A further increase in the temperature is accompanied by the transformation of titanium from the α into the β modification. At 690–720°C, the phase transformation is completed, and another hydrogen desorption peak appears in a thermally stimulated hydrogen desorption spectrum.     

Nitriding of VT1-0 titanium in low-pressure non-self-maintained glow discharge with the use of different gas mixtures

The results of nitriding of VT1-0 titanium in the plasma of non-self-maintained glow discharge with a hollow cathode are presented. A nitriding process has been implemented in different gas mixtures at low pressure and temperatures less than 650°C. It is shown that two-hour nitriding in a helium-nitrogen mixture leads to formation of a nitrided layer on the specimen’s surface. The obtained layer hardness of 14.5 GPa exceeds the hardness corresponding to pure nitrogen and argon-nitrogen nitriding by a factor of 2 and 1.5, respectively.     

Influence of a Hydrogen Atmosphere on the Properties of an Aluminum Oxide Film on VT1-0 Titanium

Technical Physics - In this study, we have considered interaction between an aluminum oxide film magnetron-sputtered on commercially pure VT1-0 titanium and a hydrogen atmosphere. The time the...     

Change of the kinetics of shock-wave deformation and fracture of VT1-0 titanium as a result of annealing

The paper presents the results of measurements of shock-wave compression profiles of VT1-0 titanium samples after rolling and in the annealed state. In the experiments, the pressure of shock compression and distance passed by the wave before emerging to the sample surface were varied. From measurements of the elastic precursor decay and compression rate in a plastic shock wave of different amplitudes, the plastic strain and the corresponding shear stresses in the initial and subsequent stages of high-rate deformation in an elastoplastic shock wave are determined. It is found that the reduction in the dislocation density as a result of annealing reduces the hardness of the material but significantly increases its dynamic yield strengh, corresponding to the strain rate above 10⁴ s^–1. With a reduction in the strain rate, this anomalous difference in the flow stresses is leveled off.     

Study of gas-mixture composition influence on structure and properties of titanium alloy VT6 at low-temperature nitriding

The influence of gas-mixture composition on structure and properties of titanium alloy VT6 (Ti-6Al-4V) at low-temperature nitriding in plasma of non-selfsustained low-pressure arc discharge is studied. The material was in two states: coarse-grained and submicrocrystalline. It is shown that mechanical properties and thickness of the modified layer depend on preliminary formed structure.     

Mechanical properties,density, and defect structure of VT1-0 titanium after intense plastic deformation due to screw and longitudinal rollings

The influence of screw rolling combined with standard methods of mechanothermal treatment on the homogeneity of the forming submicrocrystalline structure, density, and mechanical performance of VT1-0 commercial titanium is studied. It is shown that such a treatment carried out within optimal temperature and strain rate intervals (special deformation conditions) causes minor softening of the material and can be effectively used to form a homogeneous submicrocrystalline structure with high strength and elastoplastic properties.     

Study of the crystallization morphology of VT3-1 alloy during VAR

In this paper, we consider the crystallization morphology formation of VT3-1 titanium alloy in the process of vacuum arc remelting (VAR). Based on experimental data obtained by the method of autoradiography, we numerically determine remelting parameters such as the temperature gradient G at the solidification front and its velocity V. Since practically all kinds of morphology of the crystallization microstructure of metal systems are present in an ingot (planar front, cellular, cellular-dendritic, and dendritic structures), we consider two simple models of transition from one structure to another. The models greatly depend on the parameters G and V. In this paper, the liquidus curve slopes for the alloying elements of VT3-1 alloy are determined and a morphology map is constructed. Also, the results are compared with those obtained earlier by other authors.     

Study of the surface microrelief of the titanium VT18u alloy after electrochemical dimensional processing

The results of studying the titanium VT18u alloy’s surface after mechanical and electrochemical processing by scanning electron microscopy and scanning probe microscopy are presented. The influence of the phase composition and composition of the titanium alloy on the surface microrelief formed due to the pulse-cyclic electrochemical treatment in neutral water electrolytes is revealed. It is established that the method of pulse-cyclic electrochemical dimensional processing in the water solution of sodium nitrate does not result in the considerable change of the microroughness of the alloy surface.     

Strain-Induced Surface Roughening in Polycrystalline VT1-0 Titanium Specimens under Uniaxial Tension

Surface roughening in uniaxially tensile specimens of commercially pure titanium VT1-0 has been investigated using electron backscatter diffraction, optical and atomic force microscopy, and numerical simulation. It is shown that intragranular slip leads to the rotation of surface grains, due to which the grain surface is inclined and a terrace is formed at the interface with neighboring grains. The effect of the crystallographic grain orientation on the grain shape change and the degree of grain rotation occurring under constrained plastic deformation is demonstrated.     

Dielectric Losses in Hydrogen-Saturated VT1-0 Titanium Induced by Eddy Current Propagation

Technical Physics - Dielectric loss tangent tanδ in hydrogen-saturated VT1-0 titanium has been studied in the hydrogen concentration range 190–2000 ppm and eddy current frequency...     

Effect of the Structural State and Oxide Coating on the Mechanostability of VT1-0 Titanium upon Its Cyclic Loading

Physics of the Solid State - The fatigue properties of a submicrocrystalline titanium are shown to be substantially higher than those of a coarse-grained state. A deposition of an oxide coating...     

Fe40—45Cr30—35Co20—25Mo0—4Zr0—2合金微观结构对力学性能的影响

研究了高矫顽力型FeCrCo合金力学性能和微观结构间的关系.对抗弯强度和断裂韧性的测试 结果表明，高矫顽力型FeCrCo合金的力学性能远低于普通FeCrCo合金.透射电镜照片显示高 矫顽力合金的两相成分差较大；x射线衍射结果反映高矫顽力合金衍射峰强度较弱而半高宽 较大，说明高矫顽力合金中调幅分解进行彻底.合金中α₁，α₂两 相成分差的扩 大使晶格错配度增加，强度提高，韧性降低.这就是高矫顽力合金力学性能变差的原因. 关键词： 力学性能 调幅分解 抗弯强度 断裂韧性     

Effect of Small Preliminary Deformation on the Evolution of Elastoplastic Waves of Shock Compression in Annealed VT1-0 Titanium

The evolution of an elastoplastic waves of shock compression in VT1-0 titanium in the as-annealed state and after preliminary compression is measured. A preliminary strain of 0.6% and the related increase in the dislocation density are found to change the deformation kinetics radically and to decrease the Hugoniot elastic limit. An increase in the preliminary strain from 0.6% to 5.2% only weakly changes the Hugoniot elastic limit and the compression rate in the plastic shock wave. The measurement results are used to plot the strain rate versus the stress at the initial stage of high-rate deformation, and the experimental results are interpreted in terms of dislocation dynamics.     

Composition and structure of coatings formed on a VT16 titanium alloy by electro-plasma spraying combined with microarc oxidation

The composition, the structure, and the microhardness of the oxide coating formed during a combined plasma process on a VT16 titanium alloy are studied. The structure of plasma-sputtered aluminum oxide after microarc oxidation is found to change: the coating has a lower density and is melted. The phase composition of the aluminum oxide formed by electro-plasma sputtering and then subjected to microarc oxidation remains unchanged.     

Influence of thickness on optical properties of titanium layers

Titanium layers with different thicknesses of 21, 83.7, and 133 nm and same other deposition conditions were deposited on glass substrates at 300 K, by physical vapor deposition method under high vacuum conditions. The optical reflectance of the layers was measured in the wave length range of 400–800 nm. The optical properties were calculated by using Kramers-Kronig relations. Relation between the optical properties and nanostructure of the layers was investigated. By using Generalized Gradient Approximations in context of plane wave pseudopotentials (norm conserving and ultrasoft) method, band structure calculated and compared with experimental results.