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The effect of the density of grain boundaries (austenite/austenite) and phase boundaries (austenite/particle) on hydrogen embrittlement was studied in high nitrogen austenitic steel Fe-19Cr-21Mn-1.3V-0.2С-0.8N (mass %). Experiments revealed that the microscopic structural parameters such as lattice distortions, phase and grain boundaries affect the macromechanical behavior of the hydrogen-charged steel. With increasing density of grain and phase boundaries and decreasing lattice distortion of the austenitic phase, hydrogen atoms absorbed during electrolytic hydrogen charging are redistributed from interstitial positions in austenitic grains to the boundaries. This leads to a decrease in hydrogen-assisted solid solution strengthening of austenite, reduces the hydrogen-induced increase in the steel yield stress, and suppresses transgranular but promotes intergranular fracture of the hydrogen-affected layer in the tensile specimens. It was experimentally shown that an increase in the grain boundary density only, with other structural parameters unchanged, slightly improves the resistance of steel to the negative effects of hydrogen, while an increase in the total density of grain and phase boundaries has the opposite effect. [ABSTRACT FROM AUTHOR]

Temperature- and irradiation-assisted failure mechanisms in miscible phase boundaries are clarified via atomistic calculations. We first establish the temperature-dependent brittle-to-ductile transition in U–Zr miscible phase boundaries. Our results confirm that these boundaries are mostly brittle at low temperatures and ductile at elevated temperatures. We then investigate the changes induced by irradiation on the fracture mechanisms in such phase boundaries. The irradiation-induced defect accumulation follows a multi-stage process that starts with the accumulation of isolated small dislocation loops before transitioning to the saturation and growth of larger dislocation loops and end up with a reorganization into forest dislocations. The accumulation of loops is the primary feature to participate in the delineation between brittle and ductile interfacial fracture in irradiated phase boundaries. At low damage levels, radiation defect interactions with the crack tip are limited and U–Zr miscible boundaries fail through the emission of dislocations ahead of the crack tip followed by brittle cleavage in agreement with the classical Griffith's criterion for crack stability. At higher damage levels, the failure mode transitions from brittle crack growth to ductile void growth. In this case, the microcrack tip is blunted by the high density of pre-existing, radiation-induced defects in the vicinity of the crack. This interaction leads to the development and growth of a cavity at the interface as opposed to interfacial cleavage. [ABSTRACT FROM AUTHOR]

Partial and integral thermodynamic functions of the mixing and evaporation of nickel–calcium melts are calculated from the values of calcium vapor pressure at 900–1300°C (1173–1573 K), determined using the boiling points approach (isothermal version), and those of nickel, found via numerical integration of the Gibbs–Duhem equation. It is established that the formation of alloys containing up to 65.5 mol % calcium (the rest is nickel) is exothermic, while at higher Ca content the process is endothermic. The excess entropy of mixing is negative up to a Ca content of ∼64 mol %, testifying to a certain ordering in the melts due to the existence of associates. Using data on the pressure of a saturated vapor of calcium and nickel, the state diagram is supplemented by the fields of the coexistence of melts and vapor at atmospheric pressure and in vacuums of 1.33 and 0.7 kPa. The location of the boundaries of the fields of vapor–liquid equilibrium confirms the possibility of separation of the Ni–Ca melts by distillation in a vacuum. [ABSTRACT FROM AUTHOR]

The present contribution examines the accessibility of diffusivities across the two-phase region of an equimolar methane–propane mixture for dynamic light scattering (DLS) experiments. Heterodyne DLS experiments and theoretical calculations of the Rayleigh ratio were performed at 125 different thermodynamic states including the gas, liquid, supercritical, and the two-phase region. The present measurements document that two diffusivities can be determined simultaneously in the liquid state and saturated liquid phase for temperatures and pressures which correspond to densities larger than 1.15 times the critical density. Based on a rigorous assignment of the signals detected in this work, the slow and fast diffusivities could be associated with the Fick and thermal diffusivities. For all other thermodynamic states, a single hydrodynamic mode or signal was obtained experimentally. With the help of theoretical Rayleigh ratios as well as from the general behavior of the diffusivities as a function of temperature and pressure, the signals were identified to be related to the Fick diffusivity in the supercritical state and to a mixed diffusivity in the gas state and the saturated vapor phase. The results are discussed in connection with the behavior of the diffusivities along certain paths in the pressure–temperature projection of the phase diagram of the mixture. [ABSTRACT FROM AUTHOR]

The Bi0.5Li0.5ZrO3 and CaZrO3 co-modified (K,Na)NbO3-based ceramics, with a formula of (0.98-x)K0.4Na0.6NbO3-xBi0.5Li0.5ZrO3-0.02CaZrO3, were designed to form a rhombohedral-tetragonal phase boundary, and a conventional solid-state sintering method was employed to prepare them. X-ray diffraction analysis revealed that a pure perovskite structure could be maintained in the studied composition range 0 ≤ x ≤ 0.05. Dielectric-temperature measurements were performed to further identify the phase structure of the ceramics, which was found undergoing a gradual evolution from an orthorhombic to a rhombohedral structure with increasing x. Furthermore, a rhombohedral-tetragonal phase boundary was observed to be formed at x = 0.035, near which enhanced piezoelectric properties were obtained, with piezoelectric constant d33 = 241 pC/N and planar electromechanical coupling coefficient kp = 0.37. Additionally, an investigation was conducted of the influence of Bi0.5Li0.5ZrO3 addition on the microstructure and paraelectric-ferroelectric phase transition of the ceramics as well. We believe that the findings in this current work can deepen our understanding of the role of Bi0.5Li0.5ZrO3 in the construction of a phase boundary and improvement of piezoelectric properties for (K,Na)NbO3-based ceramics. [ABSTRACT FROM AUTHOR]

It is established that 82% of the vapor can condense into the liquid phase when calcium is evaporated from an alloy with copper at low pressures of 0.7–1.33 kPa under nonequilibrium conditions. Based on values of the vapor pressure of calcium and copper determined using the boiling point approach, a complete diagram of state is constructed that includes the condensed and vapor phases at atmospheric pressure and in vacuums of 0.7 and 1.33 kPa. The temperatures of boiling and the composition of the condensate are calculated from the boundaries of the melt–vapor phase transitions. The condensate is represented by calcium with a copper content no greater than 3.95 × 10–2 wt % and a boiling point 77–129°С higher than the melting point of Ca. It is assumed that the condensate remains in the molten state. The fundamental possibility of a liquid–vapor–liquid process that can be applied to distillation for the production of calcium is thus proved. [ABSTRACT FROM AUTHOR]

The structural transformation of thin-plate pearlite in the cold plastic deformation (drawing) of C86D steel coils with total reduction up to 83.2% is considered. In terms of the physical mesomechanics of structurally heterogeneous media, it is shown that the ferrite–cementite phase boundaries play a significant role in the localization of the deformation and the formation of fragmented mesostructure at different degrees of cold plastic deformation. The transformation of cementite in cold dynamic spheroidization is shown to be associated with the fragmentation of plates and the formation of local submicrocrystalline sections in the pearlite. [ABSTRACT FROM AUTHOR]

The ratio of the number of intra- and interphase crosslinks in the mixtures of nitrile-butadiene rubber with different content of acrylonitrile units and polyvinyl chloride was estimated from the contribution of each phase to the tensile modulus. It is shown that the number of chemical bonds between the components has a decisive effect on ozone-protective effect by a thermoplastic. The degree of crosslinking of rubber does not matter. [ABSTRACT FROM AUTHOR]

Adsorption of Co, Mn, and Fe atoms on the surface of calcite in ultrahigh vacuum and the interaction of the generated adsorption systems with water were studied by X-ray photoelectron spectroscopy. It is demonstrated that Mn and Fe atoms form CaCO3/Mn(Fe)CO3 solid solutions on calcite surface, whereas the dominant compounds of adsorbed Co atoms are CoО and Co3О4. When interacting with water, the Mn and Fe surface compounds are not appreciably modified, whereas the Co compounds are partly transformed into soluble hydroxylated complexes. [ABSTRACT FROM AUTHOR]

For TA15 titanium alloy, slip is the dominant plastic deformation mechanism because of relatively high Al content. In order to reveal the grain-scale stress field and geometrically necessary dislocation (GND) density distribution around the slip traces and phase boundaries where the slip lines are blocked due to Burgers orientation relationship (OR) missing. We experimentally investigated tensile deformation on TA15 titanium alloy up to 2.0% strain at room temperature. The slip traces were observed and identified using high resolution scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) measurements. The grain-scale stress fields around the slip traces and phase boundaries were calculated by the cross-correlationbased method. Based on strain gradient theories, the density of GND was calculated and analyzed. The results indicate that the grain-scale stress is significantly concentrated at phase/grain boundaries and slip traces. Although there is an obvious GND accumulation in the vicinity of phase and subgrain boundaries, no GND density accumulation appears near the slip traces. [ABSTRACT FROM AUTHOR]

The binary manganese-antimony (Mn-Sb) phase diagram was reinvestigated in the whole composition range using powder-XRD, DTA and SEM-EDX. The phase boundaries and melting temperatures of the ferromagnetic phases MnSb and MnSb were modified by taking into account the new experimental data. Most of the reaction temperatures could be verified within a range of ±10 °C. Nevertheless, a few temperatures had to be revised, such as the eutectic reaction L → β- Mn + Mn Sb at 893 °C and the eutectoid reaction β- Mn → α- Mn + Mn Sb at 718 °C. The previously reported peritectic melting behavior of MnSb could be confirmed. The variation of the lattice parameters of the NiAs-( B8 ) type MnSb phase with composition was determined. A revised version of the of the Mn-Sb phase diagram is presented. [ABSTRACT FROM AUTHOR]

We generalize the classical Legendre-Hadamard conditions by using quadratic extensions of the energy around a set of two configurations and obtain new algebraic necessary conditions for nonsmooth strong local minimizers. The implied bounds of stability are easily accessible as we illustrate on a nontrivial example where quasiconvexification is unknown. [ABSTRACT FROM AUTHOR]

The nonuniformity of hot plastic deformation of 08X21H5T steel is studied. Tensile tests are conducted in the vacuum chamber of the IMASH-20-75 Ala-Too machine. The samples are attached to a clamp in the chamber by means of straps. A junction of a platinorhodium-platinum thermocouple is soldered to the side surface of the sample. Air is pumped out of the chamber to a residual pressure of 5.0 × 10 mm Hg (6.7 × 10 Pa). The sample is heated to 800-1200°C by means of industrial-frequency current. The precision of temperature maintenance is ±5°C. The deformation of the austenite and ferrite phases is investigated as a function of the overall deformation of the steel and the temperature. The influence of these factors on the slip rate of the austenite and ferrite phases along the grain boundaries is also considered. The hot-microhardness ratio of the austenite and δ ferrite in 08X21H5T steel is investigated as a function of the temperature. [ABSTRACT FROM AUTHOR]

The structure, mechanical properties and fracture behavior of refractory alloy Kh65NVFT are studied. The causes and different mechanisms of fracture are determined as a function of temperature correlated to the cold-shortness threshold. [ABSTRACT FROM AUTHOR]