Presence Of Dislocations Research Articles

Thermodynamically consistent model of dislocation-mediated plasticity

ABSTRACT We present a thermodynamically consistent damage theory of deformation where the damage mechanism is determined by the presence of dislocations and their motion is the origin of plasticity. The damage parameter is proportional to the square root of the dislocation density of a network. For the evolution of damage, a gradient-flow equation, which describes the relaxation process of plastic deformation, is derived. Analysis shows that the dislocation-mediated plasticity is an activated process with upper and lower yield points, as opposed to a barrierless plasticity with a single yield point, which may be realised by other mechanisms of deformation. Dislocation nucleation is not a limiting factor of the dislocation-mediated plasticity because the free energy barrier for the nucleation is rather low. Application of the theory to the description of uniaxial deformation revealed many features of the experimentally observed deformation processes of metals, e.g. three stages of strain hardening with various characteristics dependent on the material and rate of loading. Applications of the theory to processes of dynamic loading of materials, which simultaneously undergo phase transformations, can bring deeper understanding of the material behaviour.

Nanoscale Operando Imaging of Electrically Driven Charge-Density Wave Phase Transitions.

Structural transformations in strongly correlated materials promise efficient and fast control of materials' properties via electrical or optical stimulation. The desired functionality of devices operating based on phase transitions, however, will also be influenced by nanoscale heterogeneity. Experimentally characterizing the relationship between microstructure and phase switching remains challenging, as nanometer resolution and high sensitivity to subtle structural modifications are required. Here, we demonstrate nanoimaging of a current-induced phase transformation in the charge-density wave (CDW) material 1T-TaS2. Combining electrical characterizations with tailored contrast enhancement, we correlate macroscopic resistance changes with the nanoscale nucleation and growth of CDW phase domains. In particular, we locally determine the transformation barrier in the presence of dislocations and strain, underlining their non-negligible impact on future functional devices. Thereby, our results demonstrate the merit of tailored contrast enhancement and beam shaping for advanced operando microscopy of quantum materials and devices.

Ni4Ti3 precipitates formed in NiTi alloy modulated by powder bed fusion and their effects on mechanical and electrical deformation

In this study, NiTi alloys featuring different distributions and morphologies of Ni4Ti3 precipitates were developed via powder bed fusion (PBF) technology. The effects of these Ni4Ti3 precipitates on the mechanical, resistive, and electrical deformational properties of the alloys were also studied. With increasing laser energy density, a coarsening behavior of the semi-coherent Ni4Ti3 precipitates was observed, with these precipitates transitioning from needle-like to disk-like structures. Consequently, their coherence with the B2 matrix diminished, thus weakening the surrounding strain field. The presence of dislocations and uniformly dispersed Ni4Ti3 precipitates, endowed the NiTi alloy with enhanced resistivity (7.294 μΩ·m) and stable tensile recovery strain (2–4 %) during stress-controlled loading and unloading. Employing PBF, a NiTi spring actuator was produced, capable of lifting loads over 145 times its weight, with a shape-memory recovery efficiency of 76.80 % at a current of 3.0 A. This study demonstrated the versatility of PBF technology in tailoring the microstructure of NiTi alloys by adjusting the laser energy density, providing a laboratory reference for advanced applications in electrically induced deformation.

Improved corrosion and cavitation erosion resistance of laser-based powder bed fusion produced Ti-6Al-4V alloy by pulsed magnetic field treatment

The application of pulsed magnetic field (PMF) treatment demonstrated enhanced corrosion resistance in saline solution and prolonged resistance to cavitation erosion in deionised water for Ti-6AI-4V alloy manufactured by laser-based powder bed fusion (LPBF) and conventional wrought processing methods. The observed outcomes were attributed to the formation of a denser protective surface oxide layer and microstructural changes, resulting in a reduction of the α' phase by 0.13% and an increase in the presence of dislocations at the surface. Consequently, this led to an increase in the compressive residual stresses. Additionally, the application of this treatment resulted in the formation of highly refined and uniform precipitates, leading to a notable enhancement in microhardness by 5.73% and 5.85% for the conventionally manufactured (CM) and LPBF samples, respectively.

Unravelling the mechanisms of copper precipitation-induced strengthening in austenitic stainless steels: An atomistic approach

Copper addition in austenitic stainless steel is known to provide good high-temperature strength through precipitation strengthening. However, the mechanism of such strengthening and its overall contribution to strength in austenitic stainless steels have not been adequately investigated. The present work employs molecular dynamics (MD) simulation to investigate the interaction between an edge dislocation and copper precipitate in austenitic stainless steel. The mechanism controlling the strength was found to be trailing partial detachment for smaller precipitates up to a maximum radius of 3 nm, whereas leading partial detachment controls the strength for larger precipitate sizes, irrespective of the inter-precipitate spacing. Besides, modulus strengthening was identified as the primary strengthening contributor for the coherent Cu precipitate in the present alloy, which was subsequently aligned with the theoretical predictions by the existing Russell-Brown (R-B) model, adopting some modifications. The discrepancy between the simulation results and the original R-B model is attributed to the interaction between the two partial dislocations in presence of the precipitate. The modified R-B model was then used in combination with Thermo-calc and DICTRA predictions to estimate the strength of Cu-added austenitic stainless steel. However, the predictions overestimated the experimental data due to the model's inability to account for the random distribution of precipitates. To address this limitation, a subsequent discrete dislocation dynamics (DDD) simulation was conducted, incorporating a random distribution of Cu precipitates. Finally, the DDD simulation results demonstrated a good match with the experimental results, which can be further extended to other alloy systems as well.

Reduction of the initial defects generated during casting of quasi-single crystalline silicon by reserving gaps between seed crystals

The presence of dislocation is a significant impediment to enhancing the quality of quasi-single crystalline silicon cast by seed-assisted directional solidification. A novel approach was proposed to reduce dislocations in G7 166-type silicon ingots, especially in the region of seed crystal seams, by reserving seed crystal gaps during loading. We calculated that the seed crystal's linear thermal expansion after heating from 298.15 to 1683.15 K was 0.9 mm. However, in consideration of the actual deviation in seed processing and measurement, we increased the gap between seeds to 1.2 mm to prevent compressive stress on all 49 seed crystals. The actual residual seed gap measured after ingot casting was approximately 0.325 mm, which is relatively close to the calculated value. It was discovered that the average defect ratio in the silicon blocks decreased from 26.95% (without gaps) to 6.79% (with 1.2 mm seed gaps) for the proposed method. This indicates that a portion of the dislocation source was reduced by reducing compressive stress caused by linear expansion between adjacent unmelted seeds. The average conversion efficiency of the solar cells prepared using the gapless seed method for p-type polycrystalline cells is 22.03%, whereas the novel approach resulted in an average cell efficiency of 22.22%, featuring a higher proportion of high-efficiency sections.

Effect of large pre-deformation on microstructure and mechanical properties of 7B52 laminated aluminum alloy

With the continuous upgrade of weapons, improving the mechanical properties of 7xxx laminated aluminum alloys for tank armor is a very important task. In this study, the 7B52 laminated aluminum alloy was strengthened through the successive solution treatment, large pre-deformation of 50%, and aging process. The yield strength, ultimate tensile strength, and interlaminar shear bonding strength of this alloy remarkably increased to 558 MPa, 593 MPa, and 93.8 MPa, respectively, which exceeded the values obtained after the traditional solution and aging processes. The effect of the large pre-deformation on the microstructural evolution and mechanical behavior of the 7B52 alloy was examined as well. The mechanical properties depended on the presence of dislocations, low-angle grain boundaries, and tiny precipitates in the alloy structure. The introduction of numerous dislocations and low-angle grain boundaries via large pre-deformation were beneficial for the full precipitation of tiny precipitates during the aging process. According to theoretical calculations, precipitation and dislocation strengthening were the dominant strengthening mechanisms. Moreover, because of its finer grain size, higher dislocation density, and larger number density of precipitates, the 7A62 alloy exhibited higher strength increments than those of the 7A52 alloy after pre-deformation. Therefore, a large pre-deformation may serve as an effective method for improving the mechanical properties of 7xxx laminated aluminum alloys for their application in the military industry.

In Ukrainian

Investigating the formation of inversion layers (IL) at the Si-SiO2 interface in the manufacturing technology of silicon photodetectors, some dynamics of dislocations after isothermal annealing were revealed, which were absent in samples without inversion. After selective etching of samples with inversion layers, localization of dislocations on the periphery of responsive elements (RE) with accumulation of guard rings (GR) or other elements of n+-type topology outside the RE was observed. This testified to the movement of dislocations on the surface of the Si-SiO2 structures with IL in the direction of the periphery of the crystal during isothermal annealing, which contributed to a significant decrease in the density of structural defects in RE. The described phenomenon can be used to obtain highly doped defect-free silicon structures. Since the presence of dislocations or other violations of the crystal lattice negatively affect the parameters of the products. In the case of using the described phenomenon as a technological method of “cleaning” the surface of silicon structures, there is a need for controlled formation of IL. One of the methods of forming inversion layers can be thermal oxidation in hydrochloric acid vapors according to the principle of dry-wet-dry oxidation (for p-type silicon). Another method that does not require additional materials is the annealing of Si-SiO2 structures at a temperature of 900–950 Celsium degrees in a nitrogen atmosphere for ≥ 240 minutes. Inversion channels, in this case, will be formed due to the redistribution and diffusion of metal impurities in the oxide (which were introduced during previous thermal operations) to the Si-SiO2 interface. In the described case, these structural defects after annealing were localized in the GR, which is also an active element of the phododiodes, as it limits the dark current of the RE, accordingly, the dark current of the GR should also be low. To be able to implement this method, it is necessary to create passive n+-regions on the periphery of the crystals, limited by oxide, which will be the locations of defects after annealing. It can be both separate areas of arbitrary shape and a concentric ring outside the GR. Elements that will be the locations of defects on the periphery can be cut off at the stage of separating the substrates into crystals. After annealing, it is necessary to remove the IL and form an anti-reflective coating by any known method, since the presence of inversion channels contributes to the growth of dark currents. When examining the morphology of defect localization areas after annealing under high-magnification microscopes and with the help of an atomic force microscope, the formation of hexagonal and round defects, which are partial marginal Frank dislocation loops, was observed. The mechanism of dislocation movement described in this article has not been thoroughly studied by us and requires additional research, but it may be related to Cottrell atmospheres and their interaction with IL

Void growth in metal anodes in solid-state batteries: Recent progress and gaps in understanding

Stripping of metal cations from the anode of a Li- or Na-ion cell into a ceramic electrolyte results in the formation of voids on the electrolyte/electrode interface. Such voids have been observed to grow to sizes in excess of 100 μm. Dendrites can nucleate and grow in the electrolyte from the vicinity of the voids during the plating phase of cycling of the cell, and lead to short-circuiting of the cell. Current theoretical understanding of the formation of these voids is in its infancy: the prevailing qualitative notion is that voids form within the metal anode when the stripping current density removes metal from the interface faster than it can be replenished. We review models that employ the Onsager formalism to develop a variational approach to model void growth by coupling power-law creep of the metal electrode and the flux of metal cations through a single-ion conductor solid electrolyte. These models, based on standard Butler-Volmer kinetics for the interfacial flux, predict that voids will shrink for realistic combinations of interfacial ionic resistance and electrolyte conductivity. Additional physics in the form of modified kinetics, such that the interfacial resistance is decreased by the presence of dislocations within the creeping metal electrode, are shown to give rise to initial growth of voids around impurity particles on the electrolyte/electrode interface. However, these voids ultimately collapse under the imposed stripping fluxes and no conditions have been identified for which isolated voids grow to more than 10μm in size. This is in contrast to the experimentally observed sizes of ∼ 100μm. The physical processes by which large voids form remain unclear but the current state-of-the-art understanding does provide clues of possible mechanisms that have not as yet been considered.

Proton and gamma irradiation of novel tungsten boride and carbide candidate shielding materials

Low-activation cWC and RSBs show considerable promise as broad-spectrum radiation-dense materials suitable for use in compact spherical tokamaks (cSTs). The radiation response of novel radiation dense materials cemented tungsten carbide (cWC) and reactive sintered borides (RSBs) at ambient and non-ambient temperatures is investigated for the first time in this work.Sample irradiation consisted of 1.5 MeV protons at 408 K and at 873 K and 60Co gamma irradiation at 293 K and 77 K. Evaluation of radiation-induced damage via electron backscatter diffraction (EBSD) and TEM observed that cWCs have greater radiation attenuation than RSBs but RSBs have more diffuse dislocation distributions. Temperature at irradiation was observed to have a significant impact on dislocation presence with more diffuse dislocation presence in RSBs at 873K but with a well-defined damage front in cWCs as determined by changes in band contrast and indexing in EBSD and by dislocation presence in TEM. Dislocation presence observed to be significantly phase-dependant, particularly for cWC where the WC phase acts to absorb the bulk of radiation-induced dislocations. Both cWC and RSBs demonstrated significant γ-ray attenuation at 77 K with most radiation-induced changes confined to the top 25 µm from the incident face.

Linear complexions directly modify dislocation motion in face-centered cubic alloys

Linear complexions are defect phases that form in the presence of dislocations and thus are promising for the direct control of plasticity. In this study, atomistic simulations are used to model the effect of linear complexions on dislocation-based mechanisms for plasticity, demonstrating unique behaviors that differ from classical dislocation glide mechanisms. Linear complexions impart higher resistance to the initiation and continuation of dislocation motion when compared to solid solution strengthening in all of the face-centered cubic alloys investigated here, with the exact strengthening level determined by the linear complexion type. Stacking fault linear complexions impart the most pronounced strengthening effect, as the dislocation core is delocalized, and initiation of plastic flow requires a dislocation nucleation event. The nanoparticle and platelet array linear complexions impart strengthening by acting as pinning sites for the dislocations, where the dislocations unpin one at a time through bowing mechanisms. For the nanoparticle arrays, this event occurs even though the obstacles do not cross the slip plane and instead only interact through modification of the dislocation's stress field. The bowing modes observed in the current work appear similar to traditional Orowan bowing around classical precipitates but differ in a number of important ways depending on the complexion type. As a whole, this study demonstrates that linear complexions are a unique tool for microstructure engineering that can allow for the creation of alloys with new plastic deformation mechanisms and extreme strength.

Gliding of conducting dislocations in SrTiO3 at room temperature: Why oxygen vacancies are strongly bound to the cores of dislocations

It is well known that the presence of dislocations in solids determines their mechanical properties, such as hardness and plasticity. In the prototype transition metal oxide SrTiO3, dislocations also influence the electronic properties, as they can serve as preferential sites of reduction processes, e.g., supporting the evolution of metallic filaments upon thermal reduction. This indicates that there is a strong interaction between the dislocations and oxygen vacancies formed upon reduction. The latter are locally-compensated by electrons. In order to investigate this interaction, in this study, we analyze the influence of mechanical stress on an already-existing dislocation-based network of conducting filaments in a single crystal. We demonstrate that plastic deformation at room temperature not only modifies the arrangement of dislocations but also conductivity at the nanoscale. This indicates that there is a strong attraction between oxygen vacancies and dislocations, such that the movement of metallic filaments and dislocations under mechanical stress is inseparably coupled.

Realization of an ultra-low lattice thermal conductivity in Bi2AgxSe3 nanostructures for enhanced thermoelectric performance

Bismuth Selenide is a Tellurium free topological insulator in V-VI compounds with an excellent thermoelectric performance from room temperature to mid-temperature region. Herein, hydrothermally prepared polycrystalline Bi2AgxSe3 nanostructures have been reported for thermoelectric application. The crystal structure identification and morphology with the elemental presence were analyzed by XRD (X-ray diffraction), HR-SEM with EDS (High resolution scanning electron microscope with energy dispersive X-ray), and HR-TEM (High-resolution transmission electron microscope) measurements. The reduced lattice thermal conductivity and enhanced electrical transport properties synergistically boost the thermoelectric properties through the highly-dense stacking faults with the presence of dislocations. The IFFT (Inverse Fast Fourier Transform) pattern reveals the existence of stacking faults and dislocations. These highly dense stacking faults and dislocations act as active phonon scattering centers, which can contribute to effective phonon scattering resultsin extremely low lattice thermal conduction of 0.3 W/mK at 543 K. On the other hand, the involvement of phonon–phonon scattering primarily reduced the lattice thermal conductivity at elevated temperatures. In addition, phonon-carrier scattering was less compared to phonon–phonon scattering at elevated temperature region. Moreover, the enhancement of electrical conductivity and controlled reduction of the Seebeck coefficient plays a vital role in achieving the maximum power factor of 335 μW/mK2 at 543 K due to the energy filtering effect. The synergistic combination of low thermal conduction and the maximum power factor helps to achieve the high peak zT of 0.3 at 543 K.

Investigation of Facetted Growth in Heavily Doped Silicon Crystals Grown in Mirror Furnaces

Herein, facets and related phenomena are studied for silicon crystals grown in the <100> and <111> directions, using the Zone Melting and Floating Zone techniques. Investigating the central facets of dislocation-free <111> crystals as a baseline allowed for the determination of the local temperature gradients. When comparing these results to dislocated <111> crystals, the presence of dislocations caused a clear reduction in the facet size, correlated with a reduction in the required local supercooling to estimated maximum values of around 0.6 K. Furthermore, for crystals grown on the rough {100} interface, attempts to provoke a morphological instability of the local phase boundary succeeded for crystallization velocities in the range of 10–16 mm/min, in good agreement with theory. Contrary to this observation, crystals grown in the <111> direction remained morphologically stable even at higher crystallization velocities due to the stabilizing effect of the atomically smooth interface. Additionally, crystals grown in the <111> direction with an oxygen skin by the Zone Melting technique reproducibly showed a non-periodic fluctuation of the central facet diameter at a certain translation velocity.

Density-gradient mechanism of vortex plastic creep

The electromagnetic response of type-II superconductors exposed to a magnetic field is governed by the dynamics of the vortex matter. We found that there exists a force of non-Peach-K\"ohler type which acts on edge dislocations in vortex lattices and depends on the gradients of vortex density. This force is absent in atomic solids where the density of the crystal lattice is constant even in the presence of dislocations. By mapping the classic theory of dislocations onto vortex lattices, we find the critical current ${j}_{c}^{\text{pl}}$ and the activation energy ${U}_{\text{pl}}$ associated with the dislocation-mediated plastic creep. The latter proves to decrease with magnetic field as ${B}^{\ensuremath{-}3/4}$, in concordance with experimental data. Such behavior of ${U}_{\text{pl}}$ is just opposite to the case of elastic (collective) creep, where ${U}_{\text{el}}$ always grows with $B$. At high enough field ${U}_{\text{pl}}$ becomes less than ${U}_{\text{el}}$, thus plastic creep overwhelms the elastic one and becomes the dominant mechanism of vortex mobility. This explains the appearance of the ``fishtail'' (double-peak) shape of magnetization curves in high-${T}_{c}$ superconductors.

Refinements for Bragg coherent X-ray diffraction imaging: electron backscatter diffraction alignment and strain field computation.

Bragg coherent X-ray diffraction imaging (BCDI) allows the 3D measurement of lattice strain along the scattering vector for specific microcrystals. If at least three linearly independent reflections are measured, the 3D variation of the full lattice strain tensor within the microcrystal can be recovered. However, this requires knowledge of the crystal orientation, which is typically attained via estimates based on crystal geometry or synchrotron microbeam Laue diffraction measurements. Presented here is an alternative method to determine the crystal orientation for BCDI measurements using electron backscatter diffraction (EBSD) to align Fe-Ni and Co-Fe alloy microcrystals on three different substrates. The orientation matrix is calculated from EBSD Euler angles and compared with the orientation determined using microbeam Laue diffraction. The average angular mismatch between the orientation matrices is less than ∼6°, which is reasonable for the search for Bragg reflections. The use of an orientation matrix derived from EBSD is demonstrated to align and measure five reflections for a single Fe-Ni microcrystal via multi-reflection BCDI. Using this data set, a refined strain field computation based on the gradient of the complex exponential of the phase is developed. This approach is shown to increase accuracy, especially in the presence of dislocations. The results demonstrate the feasibility of using EBSD to pre-align BCDI samples and the application of more efficient approaches to determine the full lattice strain tensor with greater accuracy.

Void growth within Li electrodes in solid electrolyte cells

The growth of voids at the electrode/electrolyte interface of a solid state Li battery is analysed by establishing a framework that uses the Onsager formalism to couple the power-law creep deformation of the Li electrode and flux of Li+ through a single-ion conductor solid electrolyte. For realistic combinations of the interfacial resistance and electrolyte conductivity, standard Butler-Volmer kinetics for the interfacial flux does not provide sufficient flux focussing to initiate void growth and so a modified kinetics is adopted where the interfacial resistance is decreased by the presence of dislocations within the creeping Li electrode. Micron-sized pre-existing voids shrink under stripping conditions as flux focussing on the periphery of these voids is always low. However, spatially inhomogeneous creep in the electrode around a hemispherical impurity particle reduces the interfacial resistance with consequent significant flux focussing at the periphery of the impurity. This flux focussing results in void growth with two distinct regimes of behaviour: (i) at low currents stable but small voids form while (ii) at higher currents large voids form but these ultimately collapse. No conditions are identified for which isolated voids are predicted to grow larger than 10μm in size suggesting that cell failure does not occur by the growth of isolated voids. We therefore propose a hypothesis for the coalescence of voids that initiate around impurity particles being deposited on the interface during stripping of the electrode. The ensuing predictions are consistent with measurements of cell failure and provide clues of the failure mechanisms due to void growth.

The effects of dose, dose rate, and irradiation type and their equivalence on radiation-induced segregation in binary alloy systems via phase-field simulations

Radiation-induced segregation is a phenomenon commonly observed in many alloys which consists of the redistribution of elements (solute or interstitial impurities) under irradiation. The onset and development of radiation-induced segregation can only occur when a sufficient flux of defects is sustained and defect sinks are present. Irradiation dose, dose rate, and particle types all affect defect flux. In this work, we employ a phase-field model to examine the effects of dose, dose rate, and type of incident particles on radiation-induced segregation behavior in a model binary alloy. The phase-field model takes into account the formation and evolution of point defects as well as defect clusters, the diffusion and clustering of alloy species, the presence of additional extrinsic defect sinks in the form of dislocations, and two different methods of radiation-damage insertion, which are intended to simulate either light-ion/electron irradiation via Frenkel pairs or heavy-ion irradiation in the form of cascades. Our results show a dose-rate and particle-type dependence on the amount of solute segregation. We show that the material systems exposed to higher dose rates are less subjected to solute segregation at equivalent doses. We also show that such dose-rate-dependence behavior is due to a delay of the incubation dose at which radiation-induced segregation effectively starts. Particle type and the presence of dislocations can accentuate this behavior. Our model predictions correlate with many experimental observations made over the years on radiation-induced segregation providing credence to the simulation results. The methodology presented in this study allows for a first-order prediction of the dose rate at which proxy irradiation experiments could be performed to approximate radiation-induced segregation behaviors seen in targeted irradiation conditions.

Tensile properties of cross cryo-rolled and room temperature rolled 6063 Al alloy

In the present work, 6063 Al alloy was subjected to cross cryo-rolling (XCR) at liquid nitrogen and room temperature for producing the ultrafine grained Al alloy. The XCR and cross room temperature rolling (XRTR) were performed by doing a reduction of 90%. The mechanical properties were investigated by measuring the hardness and tensile properties of investigated alloys. The increases in the average ultimate tensile strength (332 MPa), yield strength (300 MPa), and ductility (11.66%) of the XCR sample were observed as compared to the XRTR sample. The increase in the strength of the XCR sample was due to the extensive dislocation strengthening as compared to the XRTR sample. The increase in the ductility of the XCR sample was due to the softening mechanism dominated during the rolling. The microstructural properties were reported with the help of transmission electron microscopy (TEM), scanning electron microscopy and X-ray diffraction analysis and correlated with the mechanical properties. The TEM investigation revealed that XCR promotes the formation of heavily deformed sub-grains, dislocation tangles, and fragmented initial grains. The presence of dislocations inside the XRTR sample was low as compared to the XCR sample. It was observed that cross rolling at liquid nitrogen temperature further helped in the accumulation of a large number of dislocations and further improved the strength of 6063 Al alloy by suppressing the dislocations annihilations.

Modeling magnetization processes in steel under stress using magnetic objects

The application of ferromagnetic steel products is pervasive in society, with important applications arising in electrical steel, oil and gas pipelines, transportation infrastructure, naval structures, aircraft landing gear, and automotive components. Magnetic properties of electrical steel materials play a key role in electrical motors and transformers, with a direct impact on energy efficiency. Measurement of response to magnetization has implications for non-destructive inspection methods, such as magnetic flux leakage, magnetic Barkhausen noise, and metal magnetic memory method. Examples include flaw detection, characterization of material properties, and identification of stress state in steel. An understanding of the magnetic response of steel materials can be facilitated by the use of magnetic objects (MOs). MOs are defined as regions of relatively independent magnetic behavior, typically about the size of a grain, to which fundamental magnetic energy considerations may be applied. This Tutorial outlines mechanisms by which MOs may be applied for modeling magnetic response in steel and presents examples of their application. MOs incorporate material physical properties such as microstructure, grain size, crystallographic texture, the presence of dislocations and impurity elements, and the presence of residual stress and stress load on the component. They can also accommodate a description of the evolution of magnetic domain structure under magnetizing conditions. As the MO model incorporates fundamental physics principles, it allows estimates of physical parameters that can be used to provide insights into the connections between magnetic properties and material properties, including hardness, embrittlement, and the presence of applied and residual stress. Practical applications include non-destructive characterization of the stress state of steel and an improved understanding of magnetic processes in electrical steel. Examples where such models may be applied include magnetic Barkhausen noise and magnetic memory method for the characterization of steel materials. This Tutorial summarizes recent advances in the MO model and its applications, providing the foundation for its further development. Magnetic objects have the potential to provide fundamental explanations and could form the basis for magnetic measurements and magnetization processes, including magnetic flux leakage, magnetic Barkhausen noise, and magnetic hysteresis.