A. G. Illarionov

Effect of aging on structure and properties of quenched alloy based on orthorhombic titanium aluminide Ti2AlNb

Phase and structural transformations that occur upon the aging of a titanium alloy based on the O phase have been investigated. The formation of a special type of arrangement (zigzag or packet ensembles) of the O-phase plates that arise in the course of the β → O transformation has been detected. Using transmission electron microscopy, the multistage character of structural changes during the α2 → O transformation has been studied, and a schematic of the occurrence of the transformation has been proposed. The microdurometric characteristics of the indicated alloy that were obtained after different aging regimes have been estimated.

Effect of quenching temperature on structure and properties of titanium alloy: Structure and phase composition

X-ray diffraction analysis and transmission and scanning electron microscopy have been used to study regularities of the formation of structure and phase composition of a VT16 alloy during its quenching. The formation of an athermal ω phase in the VT16 alloy with the initial (α + β) structure during quenching of the alloy from 800°C was found to be possible. Quenching temperatures (Tq) at which various metastable phase compositions, such as the metastable β solid solution, β + α″ + ω, β + α″, and α″ martensite, are formed have been determined to be 750, 800, 750–850, and ≤850°C, respectively. Dependences of variations in the volume fractions of phases were plotted. It has been shown that, at quenching temperatures close to the β-transus, the active growth of β-phase grains takes place at the expense of a decrease in the α-phase volume fraction.

Effect of quenching temperature on structure and properties of titanium alloy: Physicomechanical properties

Regularities of the formation of physicomechanical properties of the VT16 alloy (Ti-3.33Al-5.18Mo-4.57V, wt %) quenched after furnace and rapid heating have been established using optical microscopy, X-ray diffraction (XRD), and dynamic mechanical analysis. It has been shown that changes in the modulus of elasticity of the VT16 alloy correlate with a decrease in the volume fraction of the α phase in the structure, except for a slight increase in the modulus of elasticity (related to the presence of the ω phase) in the case when quenching temperatures of 800–825°C were used. It has been found that the use of rapid heating to the quenching temperature leads to an increase in the temperature of the alloy transition into the single-phase β state, hampers grain growth during heating for quenching at temperatures close to the polymorphic-transition temperature, and creates conditions for more efficient strengthening in the course of subsequent aging.

Effect of heat treatment and plastic deformation on the structure and elastic modulus of a biocompatible alloy based on zirconium and titanium

Transmission electron microscopy and X-ray diffraction analysis have been used to study the phase composition and structure of an IMP-BAZALM (Zr-31Ti-18Nb (at %)) biocompatible medical alloy depending on the heat-treatment conditions. An interrelation between the values of the electron concentration of phases normalized to the volume (e/anorm = e/aalloy(νβ/νphase)) and the phase composition of the alloy has been found to exist. It has been established that the appearance of the α″ and ω phases in the structure of the alloy leads to an increase in the modulus of elasticity. The greatest increase in the modulus is observed under the conditions corresponding to the formation of the ω phase.

Structural and phase transformations in a quenched two-phase titanium alloy upon cold deformation and subsequent annealing

Methods of X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and differential scanning calorimetry have been used to study the formation of the structure and phase composition upon the cold rolling of rodlike semi-finished products of the VT16 alloy quenched for martensite (Tq = Tpt − 10 K). It has been established that, with an increasing degree of elongation caused by rolling in the range under investigation, a more complete deformation-induced transformation occurs according to the scheme α″ → (α′ + βa) with the formation of a βa solid solution with an anomalously large lattice parameter because of the development of accommodation processes due to the difference in the specific volumes of the initial (α″) and arising (α′) martensitic phases. A correlation between the phase composition and the microhardness and elastic characteristics has been established. The temperature intervals of the occurrence of the processes of solid-solution decomposition have been determined upon the continuous heating in the quenched and cold-rolled states.

Interrelation of Crystallographic Orientations of Grains in Aluminum Alloy AMg6 Under Hot Deformation and Recrystallization

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.

Effect of hydrogen on the structure of quenched orthorhombic titanium aluminide-based alloy and phase transformations during subsequent heating

The effect of hydrogen on structure formation and changes in the volume fractions of phases in an alloy based on orthorhombic titanium aluminide (O phase) alloy upon its quenching is studied. X-ray diffraction analysis is used to determine the lattice parameters of phases. It has been shown that hydrogen is dissolved mainly in the β0 phase. Differential thermal analysis is used to determine stages and temperature ranges of phase transformations during heating; it was found that introduced hydrogen shifts the β0 → O and reverse O → β0 transformations into the low-temperature range; the enthalpies of transformation are calculated.

Development and investigation of the structure and physical and mechanical properties of low-modulus Ti-Zr-Nb alloys

The criteria for the optimization of chemical composition of Ti-Zr-Nb alloys have been selected that allow for obtaining materials with low elastic moduli and which have been used to melt alloys 50Ti-(50 − x) Zr-xNb, at 15 < x < 20 at %. Transmission electron microscopy and X-ray diffraction analysis have been used to study the phase composition of the as-cast alloys and alloys after homogenizing annealing. The minimum elastic modulus (69 GPa) and minimum microhardness (2440 MPa) have been found in the almost single-β-phase alloy with a maximum niobium content (17.1 at %). An increase in the volume fraction of α″ phase in the alloys with a lower niobium content (to 15 at %) promotes the growth of values of these properties. The phase transformations that occur during the continuous heating of homogenized alloys have been studied. The dependence of the temperature of the polymorphic (α + β)-β transformation on the ratio of the alloying elements in the studied alloys have been shown.

Formation of Structure, Phase Composition and Properties in a Two-Phase Titanium Alloy Upon Variation of the Temperature and Rate Parameters of Heat Treatment

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.

Effect of Microalloying, with Rem Inclusively, on the Structure, Phase Composition and Properties of (α + β)-Titanium Alloy

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.