The lack of ductility is known to be one of the major drawbacks of amorphous state. Recently, an increase in the tensile strength and ductility was found in the [Formula: see text][Formula: see text][Formula: see text][Formula: see text][Formula: see text][Formula: see text][Formula: see text]B 2 metal glass ribbon pre-annealed at [Formula: see text]-relaxation temperature. This paper analyzes the surface relief transformation observed during this process and the nature of separate inhomogeneities. The most significant effect is a flattening of the surface relief. This case was confirmed by statistical processing. Thus, the surface relief change was shown to be a clear indicator of structure relaxation process, that occurs in a metal glass ribbon well below its crystallization.

The effect has been studied of treatment with nanosecond laser pulses on the fatigue resistance of plate samples of recrystallized (grain size of the order of 2-3 μm) commercially pure titanium (grade VT1-0) under cyclic tensile loading. The results of investigations by scanning and transmission electron microscopy of the subsurface layer microstructure of the alloy under study after exposure to nanosecond laser irradiation and subsequent fatigue tests are presented. Keywords: titanium, surface, pulsed nanosecond laser irradiation, shock-wave action, fatigue properties.

The lack of ductility is known to be a major drawback in the mechanical properties of amorphous alloys. A temperature impact is often used, as a factor to improve the mechanical parameters of these thermally unstable materials. A thick Ni 82.1 Cr 7.8 Si 4.6 Fe 3.1 Mn 0.2 Al 0.1 Cu 0.1 B 2 metallic glass ribbon was subjected to a series of one-hour anneals between 50 and 700 °C. Annealing at 250 °C revealed an increase in the density of the ribbon accompanied by structure rearrangement responsible for the β -relaxation process. In addition, the metallic glass demonstrated high ductility along with high tensile strength and hardness under load. Based on the analysis of transformation of excess free volume in the vicinity of the β -relaxation temperature, a mechanism explaining the attainment of ductility maximum realized in metallic glass under loading has been proposed.

The effect of creep on changes in the structure of samples of recrystallized microcrystalline aluminum in the fracture region and at some distance from it is studied. Transmission and scanning electron microscopy have been used to study the features of the formation of a globular ultrafine-grained structure in the region of destruction with a minimum manifestation of crystallographic texture, as well as the presence of micro- and nanoporosity.

The effect of creep on changes in the structure of samples of recrystallized microcrystalline aluminum in the fracture region and at some distance from it is studied. Transmission and scanning electron microscopy have been used to study the features of the formation of a globular ultrafine-grained structure in the region of destruction with a minimum manifestation of crystallographic texture, as well as the presence of micro- and nanoporosity. Keywords: aluminum, creep, microstructure, electron microscopy, nanopores.

The results of a study of aluminum alloy AD1 in four structural states before and after severe plastic deformation are presented. Both the initial coarse-grained state (supply state) and three fine-grained states, which differ from each other in the method of obtaining, are considered. Elastic and microplastic properties (modulus of elasticity, decrement of elastic vibrations, microplastic deformation) were determined by the acoustic method of a composite vibrator. It is shown that the modulus of elasticity changes to a large extent under the influence of the evolution of internal stresses; the attenuation of ultrasound after severe plastic deformation increases due to an increase in the area of grain boundaries. Key words: AD1 aluminum, modulus of elasticity, microcrystalline aluminum, decrement of elastic vibrations, microplastic deformation.

For high-strength titanium VT1-0, the ultrafine-grained structure of which was obtained by mechanical-thermal treatment using the methods of helical and longitudinal rolling followed by annealing to relieve stress of the first kind. The effect of long - term loading in the creep mode at elevated temperature on the size and shape of grains has been studied. A similar study was previously carried out for recrystallized coarse-grained titanium transferred from the ultrafine-grained state by isothermal annealing. Based on the data obtained in the work and the previous results of the authors, the factors affecting the mechanical stability (durability) of ultrafine-grained metals obtained under severe plastic deformation were analyzed.

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 leads to insignificant increase in these properties for titanium with a submicrocrystalline and coarse-grained structures. Some peculiarities of the fatigue fracture of submicrocrystalline and coarse-grained titanium are analyzed.

The commercial purity of VT1-0 titanium was processed by the rolling process and executed at elevated, room, and cryo-temperatures. These processings led to the formation of an ultrafine-grained microstructure, with the mean grain size at a nanometer level. Some of these materials were statically annealed at a temperature of 823 K for 1 h, which led to significant subgrains and grain coarsening. The constant load creep tests in tension were carried out in argon on all states of materials, at temperatures of 648–723 K and different ranges of applied stresses. From the value of the steady-state creep rate, the control creep mechanisms were determined. The microstructure analyses were carried out via SEM and TEM. It was found that titanium prepared at elevated and room temperatures have a higher creep strength than titanium prepared at cryo-temperatures. Furthermore, the post-SPD —annealing led to a significant decrease in the creep properties. The influence of the preparation temperature on the difference of the creep behavior were discussed and explained using the microstructure analyses of the tests’ samples.

This work deals with the influence of the processing technology of ultrafine-grained titanium by the application of severe plastic deformation (SPD) on its degradation processes in creep at elevated temperatures. Commercial grade titanium heats with different content of carbon were processed by multi-stage rolling. Creep tests under constant tensile stress were performed in a protective atmosphere of argon at a temperature of 673 K with application of different stress levels. The microstructure of the fractures creep specimens were analysed by metallographic and fractographic analyses using scanning and transmission electron microscopy (SEM, TEM). Under the same creep loading conditions the heat with higher content of carbon exhibited better creep resistance due to stronger effect of precipitation hardening by titanium carbides.

It was found that the fatigue properties of submicrocrystalline titanium are significantly higher than those for its coarse-grained state. The application of the oxide coating leads to a slight increase in these properties for titanium with a submicrocrystalline and coarse-grained structure. Some features of fatigue fracture of submicrocrystalline and coarse-grained titanium are analyzed. Keywords: submicrocrystalline and coarse-grained titanium, VT1-0, fatigue, microarc oxidation.

The effect of treatment with nanosecond laser pulses on the fatigue resistance of plate samples of recrystallized (grain size of the order of 2-3 µm) commercially pure titanium (grade VT1-0) under cyclic tensile loading is studied. The results of investigations by methods of scanning and transmission electron microscopy of the microstructure of the subsurface layer of the alloy under study after exposure to nanosecond laser irradiation and subsequent fatigue tests are presented.

For high-strength titanium VT1-0, the ultrafine-grained structure of which was obtained by mechanical-thermal treatment using the methods of helical and longitudinal rolling followed by annealing to relieve stress of the first kind. The effect of long-term loading in the creep mode at elevated temperature on the size and shape of grains has been studied. A similar study was previously carried out for recrystallized coarse-grained titanium transferred from the ultrafine-grained state by isothermal annealing. Based on the data obtained in the work and the previous results of the authors, the factors affecting the mechanical stability (durability) of ultrafine-grained metals obtained under severe plastic deformation were analyzed. Keywords: creep, durability, nanopores, ultrafine-grained metals, titanium, recrystallization.

It was found that the fatigue properties of submicrocrystalline titanium are significantly higher than those for its coarse-grained state. The application of the oxide coating leads to a slight increase in these properties for titanium with a submicrocrystalline and coarse-grained structure. Some features of fatigue fracture of submicrocrystalline and coarse-grained titanium are analyzed.

Using the methods of Raman spectroscopy, optical metallography and scanning electron microscopy, combined with the measurements of tribological characteristics, special aspects of the formation of microrelief and variation of the structural-phase state of carbon coatings formed on the surface of AISI 321 heat-resistant steel by pulsed cathodic arc deposition followed by their irradiation with nanosecond laser pulses are studied.

Two commercially pure (CP) Ti heats containing the same total impurity content have been used under investigation. Both materials were subjected to the processing procedure method of severe plastic deformation (SPD). This procedure consists of two steps of hot rolling (at 673 K) and the final rolling step at ambient temperature. The difference in individual chemical contents of impurities resulted in two states, both with ultrafine-grained (UFG) microstructures. For comparison reason, coarse-grained (CG) state was prepared by annealing of UFG state at temperature 823 K/1h. Microstructure investigations were performed using scanning electron microscope equipped with EBSD unit (SEM/EBSD) and transmission electron microscopy (TEM). Constant load tensile creep tests were conducted at temperature 673 K and applied uniaxial stress of 200MPa. Creep tests were run up to the final fracture of the creep specimens. The main objective of this work was to evaluate how the synergistic effect of SPD and the resulting microstructure affects the creep behaviour and properties of the studied materials.

This article considers the results of the study of the titanium VT1-0 surface degradation (Grade-4 equivalent) for recrystallized- and ultrafine-grained states after fatigue testing. Comparative analysis of peculiarities of the titanium samples degradation was performed after coating formation by Micro-Arc Oxidation. It was found, that the coating formed by Micro-Arc Oxidation shows different degradation behaviors for recrystallized and ultrafine-grained states

The microstructure of a thin subsurface layer of VT1-0 titanium alloy samples in the initial submicrocrystalline state after exposure to nanosecond laser pulses has been studied using scanning and transmission electron microscopy (with the possibility of X-ray microanalysis).

The characteristic features of a change in the structure of samples of submicrocrystalline (SMC) technically pure titanium of VT1-0 brand after long-term annealing in a wide temperature range of 150–700°C with a duration of 0.5 to 1008 h, as well as after action by nanosecond laser pulses, are studied by transmission electron microscopy. It is found that the microstructure of the material under study remains stable during annealing for 1 h in the temperature range 150–400°C. Long-term (more than 1000 h) low-temperature annealing in the temperature range 150–190°C also does not lead to a significant change in the size of the structural elements. The action of nanosecond laser irradiation leads to additional grinding of the original SMC structure in the surface layers of the material to a depth of about 1 μm.