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The methods of optical microscopy, x-ray phase analysis and microindentation are used to study the effect of vacuum annealing at 750, 800 and 850°C on the structure, phase composition and microhardness characteristics over cross section of welded joints of unlike alloys OT4 – VT6, VT20 – VT6 and VT23 – VT6. Recommendations are developed on the temperature of vacuum annealing of the welded compositions studied, which provide gradual variation of the hardness parameters in welded joints upon transition from the matrix metal of one alloy to the other.

Titanium alloy VTI-4 based on orthorhombic titanium aluminide Ti2AlNb is studied in the initial condition and after charging with hydrogen to different concentrations. The kinetics and the rate of hydrogen release from the hydrogen-charged alloys during a 30-min hold at 900°C in a flow of a high-purity inert gas (argon) is analyzed. The curves obtained by differential scanning calorimetry and thermal gravimetric analysis are plotted under continuous heating to 1200°C in the inert argon atmosphere at a rate of 20 K/min. The microstructure of the alloy is studied.

The methods of optical and scanning electron microscopy, microhardness measurement, differential scanning calorimetry (DSC), dilatometry, dynamic mechanical analysis, and hydrostatic weighing are used to study the structure and the physical and mechanical properties (density, microhardness, modulus of elasticity, coefficient of linear thermal expansion) of cold-deformed brass LS59-1 in the initial condition and after heating to 800°C. The DSC heating curve exhibits exo- and endothermic effects due to stress relaxation and retrogression (the exothermic effect at 115 – 235°C), melting of lead segregations (the endothermic effect at about 328°C), transition of the β′-phase into a disordered β -condition (the endothermic effect with minimum at 458°C), and transition of the brass into a single-phase β -condition (the endothermic effect at 642 – 747°C with minimum at 721°C).

We study the effect of the content of oxygen (carbon) impurities on the temperature of complete polymorphic α + β→β transformation (Tpt) and a set of properties of Ti – 10% V – 2% Fe – 3% Al and VST5553 (Ti – 5% Al – 5% V – 5% Mo – 3% Cr) titanium alloys in the thermally hardened state. We determine the microstructure of the alloys by metallographic analysis and test them for tension and fracture toughness. The dependence of Tpt on the content of impurities in the analyzed alloys is determined. It is shown that the value of Tpt can be found by the method of differential scanning calorimetry whose accuracy is comparable with the accuracy of the method of test quenching. The dependences of the strength and ductile properties of the alloys in tension on the aging temperature are constructed. We also establish the relationship between the fracture toughness of the alloys and the morphology of the primary α-phase.

Regular features of variation of structure, phase composition and hardness characteristics in a β-phase-based titanium alloy Ti – 10 V – 2Fe – 3Al subjected to isothermal treatment in a melt of lead and tin for 5 sec – 32 h at 250 – 800 °C after a hold at 860 °C are considered. The types of the phases precipitated in the process of isothermal decomposition of the high-temperature β-solid solution and the dependences of the lattice constant of the β-phase and of the hardness on the temperature-and-time mode of the treatment are determined. Adiagram of isothermal decomposition of the β-solid solution in alloy Ti – 10 V – 2Fe – 3Al is plotted.

The effect of microalloying with yttrium and zirconium in the amount of 0.06 and 0.07 wt.% respectively on the formation of structure, phase composition and measured hardness characteristics of a two-phase titanium alloy of the Ti – Al – Mo – V – Cr – Fe system is studied. The laws of variation of the phase composition and structure of the alloy with microadditives in the temperature range of 700 – 950°C and during subsequent cooling in water and air are determined. The diagram of variation of the phase composition of the alloy under water quenching is plotted.

Regular features of the variation of microstructure, phase composition and measured hardness characteristics in double-phase titanium alloy VST2 subjected to an isothermal treatment in molten tin for 1 sec – 16 h at 300 – 750°C from the temperature of the β-range (1000°C) are studied. The types of the phases precipitated in the process of the decomposition of the β-solid solution and the times of the start and finish of the transformation in the studied range of isothermal holds are determined. The diagram of isothermal decomposition of alloy VST2 is plotted.

The evolution of structure and phase composition in titanium alloy VT18U under cooling from 900 – 1035°C is studied by the methods of light and electron microscopy, x-ray imaging, hardness measurement and measurement of the modulus of elasticity. The critical temperature of heating for quenching and the dependence of the volume fraction of the phases on this temperature are determined. The effect of the structural and phase state of the alloy quenched from different temperatures on the combination of its physical and mechanical properties (modulus of elasticity, hardness) is analyzed.

The structure and mechanical properties of a large-size semiproduct from alloy VST5553 treated in the BASCA mode (beta annealed, slow cooled, aged) are studied by testing for impact bending and delayed fracture. The microstructures and fracture surfaces of specimens are investigated. To intensity the processes of decomposition of the β-phase in near-boundary regions an additional heat treatment including heating within 770 – 790°C and aging at a temperature of 550 – 600°C is suggested, which raises the mechanical characteristics under delayed fracture.

Special features of formation of phase composition in alloys of the Ti – Cr and Ti – Cr – H systems are studied after hardening from the β-range (according to the equilibrium phase diagram of the Ti – Cr system) and long-term aging. The morphology of the precipitated phases is determined and schemes explaining the special features of formation of phase composition in hydrogen-containing alloys under aging are suggested. The microhardness characteristics of the alloys are shown to depend on their phase composition.

The structure and texture of a pipe from steel AMg6 produced by the method of hot pressing (extrusion) are studied. The important role of special (special and “half-special”) boundaries in the process of dynamic recrystallization is described.

The methods of light and scanning electron microscopy and x-ray diffraction phase analysis, measurements of hardness and tensile mechanical properties are used to analyze the effect of variation of the temperature and rate parameters of heat treatment on the occurrence of structural and phase transformations and variation of properties in sheets of a martensitic titanium alloy VST2. Phase and structural diagrams of the alloy are plotted for various treatment conditions as well as a diagram of variation of the volume fractions of phases in the alloy as a function of the quenching temperature. The set of the properties obtained is shown to be related to the special features of structure formation in cooling in different environments (water, air, furnace) from heating temperatures ranging within 790 – 990°C.

Structure and phase transformations in biocompatible alloy Ti – 6% Al – 7% Nb are considered in a wide temperature range and varied cooling media. Diagrams of variation of the phase composition as a function of the heating temperature and cooling rate are plotted. A method for evaluating the volume fraction of phases depending on the temperature of heating for hardening is suggested with allowance for the distribution of chemical elements in the phases and for the average composition of the alloy. Mechanical properties are determined after various modes of treatment.

Special features of formation of athermal ω-phase in titanium alloys of the Ti – Nb, Ti – V, and Ti2AlNb-base systems are considered from the standpoint of changes in the electron concentration of the β-solid solution. The conditions of formation of ω-phase with anomalous (“raft”) morphology are determined. A dislocation model explaining the morphological features is suggested. The effect of hydrogen alloying of titanium alloys on the process of formation of ω-phase in hardening is described. Amethod for computing electron concentration for titanium alloys with hydrogen is suggested.

The methods of x-ray diffraction analysis, electron microscopy, thermal analysis, and hardness measurement are used to study special features of decomposition of metastable β-solid solution in welds of titanium alloy VT19 after hardening from 950°C and aging at 430 and 500°C.

1. Warm rolling of alloy VT22 with superimposed decomposition of the β-phase not only provides a high strength but also considerably increases the ductility of the alloy, which is connected with the dissolution, disintegration, and more uniform distribution of the particles of the second phase under the deformation.

1. The data of microstructural, differential, thermal, and x-ray phase analyses and the study of the “composition— properties” dependences have been used for plotting polythermic sections of the Ti−Al−W−Zr phase diagram at a variable content of aluminum and tungsten (0–20%). 2. With an increase in the content of one of the elements, i.e., aluminum or tungsten (at a fixed amount of the other elements), the strength characteristics of alloys in the Ti−Zr−Al−W system at room and high (600–800°C) temperatures increase. The behavior of these curves changes when the aluminum content exceeds 9%; they become horizontal at 600 and 700°C and drop markedly at 800°C and at room temperature. 3. The plasticity characteristics of the alloys largely depend on their phase composition. At room temperature the values of δ and ψ of the alloy bearing 6% Al and 6% W drop jumpwise. The specific elongation decreases substantially at 600–800°C in the case of alloying with tungsten and aluminum, and the specific reduction of area decreases substantially in alloys with an aluminum additive. At 7–10% W, the value of ψ is maximum (ψ≅100%) at 700–800°C and attains almost 70% at 600°C.