Vol 61, No 1-2 (2019)

Transformations under heating, microstructure, and magnetic properties of alloys Fe_80–xCo_xZr_10–yNb_yB₁₀ (x = 0, 40; y = 2, 4, 6) obtained by melt spinning are studied by differential thermal analysis, x-ray diffractometry, scanning electron microscopy and vibration magnetometry. The effect of cobalt additions on the toughness and the coercivity of the alloys is described.

Results of a study of transportation of chromium and iron by iodine at various temperatures of diffusion chromizing of armco iron are presented. The phase transformations occurring at various temperatures of the process are described. The minimum temperature of transportation of chromium to the surface of armco iron is determined. The morphological features of the coatings are studied. The driving force of the process is determined.

The microhardness, microstructure and susceptibility to brittle fracture with respect to the CTOD parameter are studied for industrial specimens of welded joints of sheet low-carbon microalloyed steel VL EH36 Z35² with thickness 150 mm after normalizing and subsequent post weld heat treatment. It is shown that the treatment affects positively the lowering of local microhardness and elevation of resistance to brittle fracture in the coarse-grained region of the near-weld zone of the studied type of welded joint.

Diagrams of conventional yield strength and elongation of alloy V-1341T are plotted. The effect of the temperature and duration of exposure in isothermal quenching on the composition and morphology of the products of decomposition of the solid solution of the alloy after artificial aging is studied. Transmission electron microscopy is used to show that at a high temperature (400°C) and long isothermal hold the dominant inclusions in the structure of the alloy are coarse lamellar β- and Q-phases. Lowering of the temperature and shortening of the isothermal hold reduces the formation of coarse lath precipitates of β′-phase on the dispersoid and boundaries of grains and cells and yields numerous fine inclusions of a hardening β′-phase inside the grains after aging.

Commercial-purity aluminum of grade 1050 obtained by uniaxial or multiaxial compression at room temperature at deformation rates from 1.2 × 10³ to 1.0 × 10 ^{− 3} sec ^{− 1} is studied. The true strain per one pass is kept constant while the total strain amounts to 1.6 in uniaxial deformation and to 3.0 in multiaxial one. The microstructure is determined using a transmission electron microscope. The high-rate deformation is shown to be the most effective for refining the structure due to elevation of the dislocation density and suppression of the dynamic recovery.

A bimetallic reactor vessel material (steel 15Kh2MFA with austenitic cladding) is studied. The residual stresses arising in the bimetal after heat treatment are determined with the help of x-ray diffraction, acoustic and computer control techniques. The causes of the appearance of plastic strain in the specimens are assessed and the deflections and the residual stresses after quenching and annealing are determined.

The surface layers of steel ShKh15 created by pulsed laser alloying with molybdenum, tantalum and zirconium additions to a depth of over 2 mm are investigated. Qualitative and quantitative chemical analyses of the chemical composition of local dot melts are performed as well as a metallographic analysis. The microhardness of the structural components in the fusion zone is determined. The main factors affecting the distribution and depth of penetration of the refractory alloying materials into the surface layers are established.

Stability of the structure and mechanical properties of high-strength cryogenic nonmagnetic steels 10Kh19G10N6AM2 and 09Kh19G10N6AM2D2 under long-term thermocycling and multicycle mechanical loading is investigated. The mechanical properties of the steels are determined by measuring the HV hardness and testing for tensile strength and impact bending. The phase compositions and the structures of the steels are studied by dilatometry, magnetometry and x-ray diffractometry after various impacts (thermocycling, fatigue loading, and final testing for determination of mechanical properties).

The effect of structural disordering on the magnetic properties and magnetocaloric effect of amorphous (Gd₄Co₃)_1–xGe_x (x = 0, 0.05, 0.10, 0.15) alloys is studied. The structure of the ribbons after melt-spinning is determined using an x-ray diffractometer. The thermal analysis is performed with the help of a differential scanning calorimeter. The temperature of the start of crystallization is determined. The magnetic properties are measured in a PPMS-9 system. The Curie temperature and the temperature dependence of the magnetization are determined. Different models are used for describing the critical exponents of the magnetic phase transitions.

The method of orientation microscopy (EBSD) is used to study the structure and texture of low-carbon low-alloy pipe steel after thermomechanical controlled processing (TMCP) and subsequent quenching at cooling rates 100 – 700 K/sec.

The microstructure of welded joints obtained by friction stir welding (FSW) of structural steels and aluminum, copper and titanium alloys is studied. It is shown that the traditionally formed heat-affected zone is accompanied in the near-weld zone of FSW joints by a zone affected by thermal deformation (TDAZ) lying between the nugget and the HAZ. Two groups of alloys differing in the mechanism of plastic strain under FSW and affecting the formation of TDAZ and HAZ are distinguished.

Models of structure of plane Guinier–Preston zones in Al – Li and Al – Cu – Li systems are suggested. The models are based on the structural and phase correspondence of volume fragments of the structures of δ-phase of the Al – Li system and θ′-phase of the Al – Cu system to the fcc crystal structure of aluminum, which is not valid for their plane sections.

Structural and phase transformations under cooling of low-carbon martensitic steels of the Cr – Mn – Ni – Mo – V – Nb system with carbon content 0.15 and 0.27% are studied. The microstructure is investigated by optical and electron microscopy, measurement of hardness, x-ray diffraction analysis, dilatometric and energy dispersive analyses. The strength and ductility parameters are determined in tensile tests. The impact toughness is determined.

The distribution of phosphorus and sulfur impurities in the γ- and γ₁-phases of single crystals of alloy ZhS36-VI is studied by high-resolution methods of transmission electron microscopy and microscopic x-ray spectrum analysis. It is shown that these impurities are mostly concentrated in the γ-solid solution, which contains local regions of their high content. The kind of the distribution of the impurities is preserved after testing for long-term strength; the nonuniformity of the distribution of sulfur between the γ- and γ₁-phases becomes more manifested, especially for the composition with a high sulfur content.