The cyclic stability of rubber-like behaviour in stress-induced martensite aged Ni49Fe18Ga27Co6 (at.%) single crystals

In present work, the cyclic stability of the rubber-like behaviour (RLB) was investigated in Ni49Fe18Ga27Co6 (at. %) single crystals. Crystals were aged in the martensite phase at 423 K for 1 h under a compressive stress of 450 MPa, applied along the [110]B2[100]L10-direction. The RLB was induced by a preliminary chemical stabilization of the oriented L10-martensite during stress-induced martensite aging (SIM-aging) and following the reversible reorientation of martensitic variants under a compressive stress applied along the [001]B2[001]L10-direction. The high cyclic stability of the RLB was obtained in 200 loading/unloading cycles, due to the low reorientation stresses of the L10-martensite variants (no higher than 140 MPa) and the high strength properties of the L10-martensite (~1.6 GPa). The irreversible strain after 200 cycles did not exceed 0.6%. An increase in the number of cycles did not lead to the effect of destabilization of the L10-martensite

Orientation dependence of superelasticity in quenched high-nickel Ti51.8Ni single crystals

The orientation dependence of the functional and mechanical properties of quenched Ti-51.8at.%Ni single crystals, undergoing a strain-glass transition upon cooling/heating was investigated. It was found that a compressive stress above 800 MPa leads to the B2-B190 martensitic transformation (MT), regardless of orientation. In the high-strength [0 0 1]-orientation, superelasticity (SE) was observed at 203–248 K, with a reversible strain of 2.3%. Degradation of SE at deforming stresses r > 1000 MPa was associated with the formation of {1 1 3}B2 twins during the reverse MT. In the low-strength 1 1 1-orientation, the formation of stress-induced B190 -martensite occurred simultaneously with the plastic deformation of the B2-phase (due to the formation of reorientation bands and dislocation slip) and a reversible strain was not observed

Complex Study of Magnetization Reversal Mechanisms of FeNi/FeMn Bilayers Depending on Growth Conditions

Magnetization reversal processes in the NiFe/FeMn exchange biased structures with various antiferromagnetic layer thicknesses (0–50 nm) and glass substrate temperatures (17–600◦C) during deposition were investigated in detail. Magnetic measurements were performed in the temperature range from 80 K up to 300 K. Hysteresis loop asymmetry was found at temperatures lower than 150 K for the samples with an antiferromagnetic layer thickness of more than 10 nm. The average grain size of FeMn was found to increase with the AFM layer increase, and to decrease with the substrate temperature increase. Hysteresis loop asymmetry was explained in terms of the exchange spring model in the antiferromagnetic layer. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Russian Federation, Minobrnauka: FEUZ-2020-0051; Agentúra na Podporu Výskumu a Vývoja, APVV: APVV-20-0324Funding: This work has been supported by the grant of the Slovak Research and Development Agency under the contract No APVV-20-0324. This work was in part financially supported by the Ministry of Science and Higher Education of the Russian Federation, Subject of the state task No. FEUZ-2020-0051. The electron microscopy investigations were carried out on the equipment of Krasnoyarsk Regional Center of Research Equipment of Federal Research Center «Krasnoyarsk Science Center SB RAS»

Синтез, микроструктура и магнитные свойства магнитомягких пленок СоР

Soft magnetic thin CoP films were obtained by means of chemical metallization from aqueous cobalt salt solution in the presence of sodium hydroxide, citric acid and sodium hypophosphite as the reducing agent. The optimal values of the magnetic film parameters (saturation magnetization and width of ferromagnetic resonance line) were obtained by variation of composition of work solutions. It allows to reduce losses in their application in microwave devices. Microphotographs of magnetic film indicate a grain structure with a grain size of about 50 nm and presence of inclusions with the size of 3-5 nm. To determine the magnetic parameters of the investigated films the method of ferromagnetic resonance (FMR) absorption curves processing is used. The values of FMR line width and an effective magnetization of film material saturation were obtained.Приведены результаты исследования свойств магнитомягких тонких пленок СоР, полученных методом химической металлизации из водного раствора на основе цитратных комплексов с применением в качестве щелочного реагента NaOH. С помощью вариации составов рабочих растворов получены оптимальные значения магнитных параметров пленок: намагниченности насыщения и ширины линии ферромагнитного резонанса

The Clusters Self-Assembled Crystal and Magnetic Structure During the Martensite Transition in Fe86mn13c Alloy

In bulk and thin film state Fe86Mn13C alloy observed experimentally self-assembly of the crystal and magnetic structures on multiscale levels. Offered self-assembly cluster model of atomic structure based on the concept of a liquid-like state of the material in localized areas, formed in the waves of plastic deformation

Phase with Spinel Structure Type in Plastically Deformed Niti

Исследованы образцы сплава Ni51Ti49, подвергнутые пластической деформации. Микроструктура исследовалась методом просвечивающей электронной микроскопии и микродифракции на микроскопе Hitachi 7700. Для исследования образцов методами просвечивающей электронной микроскопии (ПЭМ) с зоны разрыва растянутых образцов вырезали диски диаметром 3 мм, которые механически утоняли, затем электрохимическим способом травили до появления отверстия в центре диска. Финальным этапом подготовки являлось ионное травление на установке PIPS (Gatan). Утоненные для просвечивающей электронной микроскопии образцы были подвергнуты криомеханической обработке путем циклического охлаждения в жидком азоте. Фазовый состав образцов определяли методом дифракции рентгеновских лучей в дифрактометре «Bruker» с использованием излучения меди. В зонах локализации деформации обнаружены линзовидные кристаллы фазы Ni2Ti3, содержащие изгибные экстинкционные контуры, которые свидетельствуют о значительной кривизне кристаллической решетки, появляющейся в зонах локализации пластической деформации. Показано, что кристаллическая структура линзовидных кристаллов представляет собой фазу, обладающую структурным типом шпинели с параметром кристаллической решетки 11,53±0,03 Å. Для формирования линзовидных кристаллов неравновесной фазы Ni2Ti3 необходимо перераспределение компонентов исходного твердого раствора или интерметаллидных фаз. В условиях локальной кривизны кристаллической решетки в зонах увеличенных межатомных расстояний возникают особые структурные состояния, которые повышают число степеней свободы в деформируемом твердом теле и таким образом способствуют появлению новых фазThe alloy samples Ni51Ti49, subjected to plastic deformation were investigated. The microstructure and the microdiffraction were investigated by transmission electron microscopy Hitachi 7700. Discs with a diameter of 3 mm for investigation by transmission electron microscopy (TEM) was cut from the fracture zone of the stretched sample. They were mechanically thinned, then electrochemically etched until the hole in the center. The final step was to prepare ion etching in install PIPS (Gatan). TEM specimens were subjected cryomechanical processing. This was done by in liquid nitrogen cooling cyclically. The phase composition of the samples was determined by X-ray diffraction diffractometer "Bruker" using copper radiation. The lens-form crystals Ni2Ti3, containing bending contours, indicating significant internal stresses in the zones of stress localization were detected. The lens-form crystals can be represented as a non-equilibrium phase Ni2Ti3 with spinel structure type with lattice parameter 11,53 ± 0,03 Å. For the formation of lenticular crystals of nonequilibrium phase Ni2Ti3 it is necessary redistribution of the original solid solution components. In local curvature of the crystalline lattice areas, the increased interatomic distances created the special structural states. These states increase the number of degrees of freedom in a deformable solid and thus contribute to the emergence of new phase

Tunable magnetic properties of Ni-doped CoFe2O4 nanoparticles prepared by the sol\u2013gel citrate self-combustion method

The nanostructured spinel ferrites with complex stoichiometry are an important family of the materials in a number of applications, especially in electronics through their good electrical and magnetic properties. In the framework of this study, a set of mixed cobalt and nickel ferrites was prepared with the sol\u2013gel self-combustion route. The structural and morphological features of particles were studied with X-ray diffraction (XRD), Scanning Transmission Electron Microscopy (STEM) and Energy Dispersive X-ray analysis (EDX) techniques. The prepared particles show a crystalline nature with a monotonic distribution of the elements and particles size distribution in the range of 17\u201329 nm. The obtained particles demonstrate good magnetic properties with tunable saturation magnetization and magnetic anisotropy, i.e., coercivity depending on chemical composition

Кластерная самоорганизация кристаллической и магнитной структур в процессе мартенситного превращения в сплаве Fe86Mn13C

In bulk and thin film state Fe86Mn13C alloy observed experimentally self-assembly of the crystal and magnetic structures on multiscale levels. Offered self-assembly cluster model of atomic structure based on the concept of a liquid-like state of the material in localized areas, formed in the waves of plastic deformationВ массивных и тонкопленочных образцах сплава Fe86Mn13C экспериментально наблюдается самоорганизация кристаллической и магнитной структур на разномасштабных уровнях. Предлагается кластерная модель атомной самоорганизации, основанная на концепции жидкоподобного состояния материала в локальных участках, образованных волнами пластической деформаци