The Experts below are selected from a list of 2568 Experts worldwide ranked by ideXlab platform
M. P. Kashchenko - One of the best experts on this subject based on the ideXlab platform.
-
Degenerate Structure of Transformation Twins and Estimation of Dislocation Density in Martensite Crystals
Physics of the Solid State, 2019Co-Authors: M. P. Kashchenko, N. M. Kashchenko, V. G. ChashchinaAbstract:In the dynamic theory of martensitic transformations, the wave mechanism of controlling Martensite Crystal growth is determined by the superposition of wave beams of quasi-longitudinal (or longitudinal) waves carrying the “tensile–compression” deformation in the orthogonal directions. The wave beam formation is considered to be a result of the formation of excited (vibrational) states. The existence of transformation twins is interpreted as a result of a matched propagation with respect to long-wave ( l waves) and short-wave ( s waves) shifts. The matching condition is analyzed for the γ–α martensitic transformation in iron-base alloys. It is shown for the first time that the transition to a degenerate twin structure with the allowance for the medium discreteness enables one to estimate the dislocation density in Crystals with habit {557}, which agrees with that observed experimentally.
-
Dynamic Scenarios of the Formation of Martensite with the {110} Habits in the Ni_50Mn_50 Alloy
Physics of Metals and Metallography, 2019Co-Authors: M. P. Kashchenko, E. S. Belosludtseva, N. M. Kashchenko, V. G. Chashchina, V G Pushin, A. N. UksusnikovAbstract:Martensitic transformation B 2– L 1_0 in the ordered alloy Ni_50Mn_50, which occurs at comparatively high temperatures (980–920 K), is discussed with the use of dynamic concepts of the wave control of the threshold deformation. The proximity of the observed orientations of Martensite-Crystal habits (and of twin boundaries) to the planes of the {110} family makes it possible to use the longitudinal waves along the axes 〈001〉 (in the basis of the initial phase) as the driving factors. It is shown that at temperatures of the onset of the transformation there is a satisfactory correspondence between the calculated and experimental data on the tetragonality of Martensite and on the volume effect. The opportunity of different dynamic scenarios of the formation of the final phase is noted, namely, of separate Crystals; layered structures, in which the Crystals of Martensite with the identical orientation relationships alternate with the untransformed regions of austenite; and packets of pairwise-twinned Crystals. Examples are given of morpho-types corresponding to these scenarios.
-
Inheritance of the Elastic Field of Martensite Nucleation Center by the Control Wave Process Initiating Deformations of Planes {110}c of Cubic Crystals
Metal Science and Heat Treatment, 2017Co-Authors: M. P. Kashchenko, V. G. ChashchinaAbstract:The possibility of inheritance of the elastic field in the zone of appearance of the initial excited state by the wave process controlling growth of the Martensite Crystal is shown. The case when the wave vectors of the control waves belong to plane {110}c of the original cubic phase is analyzed. Implementability of such inheritance is demonstrated with the use of elastic moduli for single-Crystal bcc titanium, which advances the predictive capacity of the dynamic theory.
-
Inheritance of the Elastic Field of Martensite Nucleation Center by the Control Wave Process Initiating Deformations of Planes {110}_c of Cubic Crystals
Metal Science and Heat Treatment, 2017Co-Authors: M. P. Kashchenko, V. G. ChashchinaAbstract:The possibility of inheritance of the elastic field in the zone of appearance of the initial excited state by the wave process controlling growth of the Martensite Crystal is shown. The case when the wave vectors of the control waves belong to plane {110}_c of the original cubic phase is analyzed. Implementability of such inheritance is demonstrated with the use of elastic moduli for single-Crystal bcc titanium, which advances the predictive capacity of the dynamic theory.
-
Promising Versions of α-Martensite Rod-Like Crystal Initiation in Iron Alloys by Three Elastic Wave Sources
Metal Science and Heat Treatment, 2016Co-Authors: M. P. Kashchenko, V. G. ChashchinaAbstract:Versions are provided for α-Martensite rod-shaped Crystal initiation by three orthogonal longitudinal elastic waves propagating in orthogonal directions of the types 〈001〉_γ and 〈110〉_γ in Fe – 31% Ni single Crystals. The probability is considered of direct initiation by Bain-type deformation waves. It is demonstrated within the scope of dynamic theory that the anticipated orientation of rod-like Crystals is close to 〈111〉_γ or to 〈905〉_γ. Possible features of Martensite Crystal tetragonality are discussed. Ultrasound source power required for initiating martensitic transformation is determined.
V. G. Chashchina - One of the best experts on this subject based on the ideXlab platform.
-
Degenerate Structure of Transformation Twins and Estimation of Dislocation Density in Martensite Crystals
Physics of the Solid State, 2019Co-Authors: M. P. Kashchenko, N. M. Kashchenko, V. G. ChashchinaAbstract:In the dynamic theory of martensitic transformations, the wave mechanism of controlling Martensite Crystal growth is determined by the superposition of wave beams of quasi-longitudinal (or longitudinal) waves carrying the “tensile–compression” deformation in the orthogonal directions. The wave beam formation is considered to be a result of the formation of excited (vibrational) states. The existence of transformation twins is interpreted as a result of a matched propagation with respect to long-wave ( l waves) and short-wave ( s waves) shifts. The matching condition is analyzed for the γ–α martensitic transformation in iron-base alloys. It is shown for the first time that the transition to a degenerate twin structure with the allowance for the medium discreteness enables one to estimate the dislocation density in Crystals with habit {557}, which agrees with that observed experimentally.
-
Dynamic Scenarios of the Formation of Martensite with the {110} Habits in the Ni_50Mn_50 Alloy
Physics of Metals and Metallography, 2019Co-Authors: M. P. Kashchenko, E. S. Belosludtseva, N. M. Kashchenko, V. G. Chashchina, V G Pushin, A. N. UksusnikovAbstract:Martensitic transformation B 2– L 1_0 in the ordered alloy Ni_50Mn_50, which occurs at comparatively high temperatures (980–920 K), is discussed with the use of dynamic concepts of the wave control of the threshold deformation. The proximity of the observed orientations of Martensite-Crystal habits (and of twin boundaries) to the planes of the {110} family makes it possible to use the longitudinal waves along the axes 〈001〉 (in the basis of the initial phase) as the driving factors. It is shown that at temperatures of the onset of the transformation there is a satisfactory correspondence between the calculated and experimental data on the tetragonality of Martensite and on the volume effect. The opportunity of different dynamic scenarios of the formation of the final phase is noted, namely, of separate Crystals; layered structures, in which the Crystals of Martensite with the identical orientation relationships alternate with the untransformed regions of austenite; and packets of pairwise-twinned Crystals. Examples are given of morpho-types corresponding to these scenarios.
-
Inheritance of the Elastic Field of Martensite Nucleation Center by the Control Wave Process Initiating Deformations of Planes {110}c of Cubic Crystals
Metal Science and Heat Treatment, 2017Co-Authors: M. P. Kashchenko, V. G. ChashchinaAbstract:The possibility of inheritance of the elastic field in the zone of appearance of the initial excited state by the wave process controlling growth of the Martensite Crystal is shown. The case when the wave vectors of the control waves belong to plane {110}c of the original cubic phase is analyzed. Implementability of such inheritance is demonstrated with the use of elastic moduli for single-Crystal bcc titanium, which advances the predictive capacity of the dynamic theory.
-
Inheritance of the Elastic Field of Martensite Nucleation Center by the Control Wave Process Initiating Deformations of Planes {110}_c of Cubic Crystals
Metal Science and Heat Treatment, 2017Co-Authors: M. P. Kashchenko, V. G. ChashchinaAbstract:The possibility of inheritance of the elastic field in the zone of appearance of the initial excited state by the wave process controlling growth of the Martensite Crystal is shown. The case when the wave vectors of the control waves belong to plane {110}_c of the original cubic phase is analyzed. Implementability of such inheritance is demonstrated with the use of elastic moduli for single-Crystal bcc titanium, which advances the predictive capacity of the dynamic theory.
-
Promising Versions of α-Martensite Rod-Like Crystal Initiation in Iron Alloys by Three Elastic Wave Sources
Metal Science and Heat Treatment, 2016Co-Authors: M. P. Kashchenko, V. G. ChashchinaAbstract:Versions are provided for α-Martensite rod-shaped Crystal initiation by three orthogonal longitudinal elastic waves propagating in orthogonal directions of the types 〈001〉_γ and 〈110〉_γ in Fe – 31% Ni single Crystals. The probability is considered of direct initiation by Bain-type deformation waves. It is demonstrated within the scope of dynamic theory that the anticipated orientation of rod-like Crystals is close to 〈111〉_γ or to 〈905〉_γ. Possible features of Martensite Crystal tetragonality are discussed. Ultrasound source power required for initiating martensitic transformation is determined.
S. D. Prokoshkin - One of the best experts on this subject based on the ideXlab platform.
-
formation of nanostructures in thermomechanically treated ti ni and ti nb zr ta smas and their roles in Martensite Crystal lattice changes and mechanical behavior
Journal of Alloys and Compounds, 2013Co-Authors: S. D. Prokoshkin, A V Korotitskiy, Vladimir Brailovski, K Inaekyan, S Dubinskiy, M R Filonov, M I PetrzhikAbstract:Abstract The processes of structure formation in Ti–Ni and Ti–Nb–Zr, Ti–Nb–Ta shape memory alloys under thermomechanical treatment were studied. The thermomechanical treatment comprised cold rolling with true strains from e = 0.25 to 2 and post-deformation annealing in the 300–900 °C temperature range. The differences in these processes between the two groups of alloys were evaluated in terms of their effect on nanostructures formation. The main conclusions are as follows: nanostructures created by thermomechanical treatment are quite useful, as they show a radical improvement of shape memory alloy functional properties. A specific nanostructure (nanoCrystalline structure, nanosubgrained structure or their mixture) should be privileged considering other structural and technological factors such as mechanical damage, formation of a brittle second phase, etc., as well as application requirements.
-
a comparative study of Martensite Crystal lattice in nanostructured quenched and deformed ti ni shape memory alloys
ESOMAT 2009 - 8th European Symposium on Martensitic Transformations, 2009Co-Authors: S. D. Prokoshkin, A V Korotitskiy, Vladimir Brailovski, K Inaekyan, S M DubinskiyAbstract:The Crystal lattices of cooling-induced (thermal) Martensites formed in thermally and thermomechanically treated Ti-Ni Shape Memory Alloys (SMA) and stress-induced, reoriented and plastically deformed Martensites were studied using the X-ray diffraction method. The linear dependences of the TXHQFKHG�%��∂ -Martensite lattice parameters (LPs), maximum transformation lattice strain in single- and polyCrystalline B2-austenites as well as its Crystallographic direction on nickel concentration in the hyperequiatomic range are presented. The lattice parameters and maximum transformation lattice strain of Martensite formed from nanoCrystalline or polygonized austenites differ from those of quenched Martensite formed from reCrystallized austenite. The averaged LPs of stress-induced, reoriented and moderately plastically deformed Martensites are close to the lattice parameters of quenched Martensite.
-
comparative x ray and time of flight neutron diffraction studies of Martensite Crystal lattice in stressed and unstressed binary ti ni alloys
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: S. D. Prokoshkin, A V Korotitskiy, Vladimir Brailovski, A V Tamonov, Yu I Khmelevskaya, S TurenneAbstract:Abstract An X-ray and time-of-flight neutron diffraction study of a Ti–50.0 at.% Ni alloy was performed. The B19′ Martensite lattice parameters are different for the quenched Martensite and for the Martensite formed from the austenite containing a well-developed dislocation substructure due to transformation-induced hardening. A tensile stress increases the “underrecovery” of the d h k l values of planes perpendicular to the axis of tension (and of the “apparent” Martensite lattice parameters calculated from these d h k l values) after a cycle of transformation-induced hardening compared with the corresponding values of the initial quenched Martensite. A probable cause for the differences between d h k l and lattice parameters of Martensite formed from highly dislocated austenite and corresponding parameters of quenched Martensite formed from reCrystallized austenite are tensile components of stress fields generated by the dislocation substructure and/or residual stresses of different origin which are present in the initial austenite.
-
Transformation of retained austenite in high-carbon steel
Physics of Metals and Metallography, 1992Co-Authors: D. E. Kaputkin, L. M. Kaputkina, Z. D. Kolev, S. D. Prokoshkin, O. Yu. TikhomirovaAbstract:Dilatometric, electron microscopic, and X-ray diffraction techniques have been employed to analyze the transformation of the retained austenite in a steel with 1.85 wt % C under tempering. The quenched steel contains 82% retained austenite. Depending on the temperature, the transformation of the retained austenite in high-carbon steel consists in the formation of a bainite «fringe» around the Martensite Crystal grains, new lenticular and thin-plate grains of isothermal Martensite also surrounded with the bainite «fringe» as well as the thin-plate pearlite
K Ullakko - One of the best experts on this subject based on the ideXlab platform.
-
modeling the strain response magneto mechanical cycling under the external stress work output and energy losses in ni mn ga
Mechanics of Materials, 2006Co-Authors: A A Likhachev, Alexei Sozinov, K UllakkoAbstract:Abstract Present publication gives a detailed theoretical concept and also presents the relevant experimental results concerning the effect of the constant external stress on the magnetic-field-controlled strain response during the cycling in magnetic field in Ni–Mn–Ga. We also first consider in details the problems of hysteresis, total energy balance, energy losses, optimization of work output and estimation of thermodynamic efficiency for Ni–Mn–Ga based MSMAs. Simultaneously we give the most important information about the main structural, magnetic and mechanical properties related to a family of non-stoichiometric Ni–Mn–Ga alloys having three different type of Martensite Crystal structures.
-
Magnetic shape memory Mechanism, modeling principles and their application to Ni-Mn-Ga
Journal de Physique IV (Proceedings), 2003Co-Authors: A A Likhachev, Alexei Sozinov, K UllakkoAbstract:This article briefly summarizes the mechanism of magnetic shape memory, main modeling principles and most important information about the main structural, magnetic and mechanical properties related to a family of non-stoichiometric Ni-Mn-Ga alloys. Depending on the Martensite Crystal structure these alloys are able to show a really giant (about 6% or 11%) strain response in a magnetic field less than 1 T.
M I Petrzhik - One of the best experts on this subject based on the ideXlab platform.
-
formation of nanostructures in thermomechanically treated ti ni and ti nb zr ta smas and their roles in Martensite Crystal lattice changes and mechanical behavior
Journal of Alloys and Compounds, 2013Co-Authors: S. D. Prokoshkin, A V Korotitskiy, Vladimir Brailovski, K Inaekyan, S Dubinskiy, M R Filonov, M I PetrzhikAbstract:Abstract The processes of structure formation in Ti–Ni and Ti–Nb–Zr, Ti–Nb–Ta shape memory alloys under thermomechanical treatment were studied. The thermomechanical treatment comprised cold rolling with true strains from e = 0.25 to 2 and post-deformation annealing in the 300–900 °C temperature range. The differences in these processes between the two groups of alloys were evaluated in terms of their effect on nanostructures formation. The main conclusions are as follows: nanostructures created by thermomechanical treatment are quite useful, as they show a radical improvement of shape memory alloy functional properties. A specific nanostructure (nanoCrystalline structure, nanosubgrained structure or their mixture) should be privileged considering other structural and technological factors such as mechanical damage, formation of a brittle second phase, etc., as well as application requirements.