In-plane Anisotropy Research Articles

Significant reduction of anisotropy in stress relaxation aging and mechanical properties improvement for 2195 Al-Cu-Li alloy subjected to plastic loading

Although the plastic loading can enhance creep deformation and yield strength, the anisotropic Stress Relaxation Aging (SRA) behavior and mechanism under plastic loading remain unclear, which presents a significant challenge in accurately shaping aluminum alloy panels. In this study, the SRA behavior of 2195-T4 Al-Cu-Li alloys were thoroughly studied under initial loading stresses within the elastic (210/250 MPa) and plastic (380/420 MPa) ranges at 180 ℃ by stress relaxation and tensile tests as well as microstructure characterization. The findings reveal that compared with those under elastic loadings, in-plane anisotropy (IPA) values of the stress relaxation amount, yield strength and fracture elongation under plastic loadings are reduced by 60%-80%, 70%-90% and 72%-89%, respectively. Similarly, IPA values of precipitate size in grains and Precipitation-Free Zones (PFZ) width at grain boundaries under plastic loading decrease by 31.4% and 94.4% respectively. These results indicate plastic loading significantly weakens the anisotropic SRA behavior, owing to numerous uniformly distributed fine T1 phases and small IPA values of both T1 precipitates size and PFZ width in various loading directions. Compared with those of elastic loading-aged alloys, yield strength of plastic loading-aged alloys shows high strength-ductility because of the combined effect of closely dispersed fine T1 precipitates, narrowed PFZ and numerous sheared and rotated T1 phases at different locations during tensile process. The uniformly distributed larger Kernel Average Misorientation (KAM) and Schmidt factor values of the plastic loading-aged alloy, as well as the cross-slip generated, also help to enhance the strength and ductility of the alloy.

Anisotropy in AISI 316L produced by Binder Jetting 3D printing: Sintering shrinkage and thermal conductivity

The inhomogeneous particle packing in green parts manufactured by Binder Jetting 3D printing is responsible for the anisotropy in several phenomena and properties. In this work, the anisotropy of the sintering shrinkage and of thermal conductivity of AISI 316L green specimens is investigated. Shrinkage was investigated by dilatometry. Moreover, the dimensional changes, density, and the thermal conductivity of specimens sintered at intermediate temperatures were measured. The microstructure of the specimens was analysed with the standard metallographic. Sintering shrinkage is basically isotropic during the heating step and becomes anisotropic on approaching the sintering temperature at 1370°C when the full density is achieved. A slight anisotropy in the building plane is observed. Contrarily, thermal conductivity is anisotropic during the heating step and becomes isotropic during the isothermal holding at the sintering temperature. Moreover, there is an inverse relationship between thermal conductivity in the debinded specimen and shrinkage. A hypothesis for this indirect correlation is proposed. The role of the large interlayer pores and the aligned pores caused by the ballistic effect of the binder jet is confirmed.

First-principles study of electronic and magnetic properties of Fe atoms on Cu2N/Cu(100)

Abstract First-principles calculations were conducted to investigate the structural, electronic, and magnetic properties of single Fe atoms and Fe dimers on Cu2N/Cu(100). Upon adsorption of an Fe atom onto Cu2N/Cu(100), robust Fe–N bonds form, resulting in the incorporation of both single Fe atoms and Fe dimers within the surface Cu2N layer. The partial occupancy of Fe-3d orbitals lead to large spin moments on the Fe atoms. Interestingly, both single Fe atoms and Fe dimers exhibit in-plane magnetic anisotropy, with the magnetic anisotropy energy (MAE) of an Fe dimer exceeding twice that of a single Fe atom. This magnetic anisotropy can be attributed to the predominant contribution of the component along the x direction of the spin–orbital coupling Hamiltonian. Additionally, the formation of Fe–Cu dimers may further boost the magnetic anisotropy, as the energy levels of the Fe-3d orbitals are remarkably influenced by the presence of Cu atoms. Our study manifests the significance of uncovering the origin of magnetic anisotropy in engineering the magnetic properties of magnetic nanostructures.

Modification of magnetoelectric properties of thin film composite multiferroics of Fe10Ni90/PVDF type with using nanostructured Fe10Ni90 layer

In this work, we study the effectiveness of using nanostructuring of a magnetostrictive Fe10Ni90 layer in a film composite multiferroic of the [Fe10Ni90/Cu]p/Fe10Ni90/PVDF type in order to obtain the maximum magnetoelectric effect (ME) while maintaining the high magnetosensitivity characteristic of thin Fe10Ni90 films. In this case, such nanostructuring parameters as the number of periods p and the thickness LFeNi of the Fe–Ni sublayers were varied. The analysis of the dependences of the ME coefficient αE on the indicated parameters carried out in this work made it possible to identify the optimal configuration of the multiferroic. Thus, the work shows that in the non-resonant mode the highest ME coupling coefficient (αE = 4.2 V/cm∙Oe) is achieved for a structure with p = 4 and LFeNi = 200 nm in a saturation field of ∼50 Oe, and a close to linear change in αE is realized in the field range 6–15 Oe. At the same time, this structure retains a low coercive field Hc ∼ 4–5 Oe and pronounced uniaxial magnetic anisotropy in the film plane. These facts indicate the absence in the magnetic component of the multiferroic structure of an undesirable “supercritical” magnetic state, which appears in unstructured Fe10Ni90 films with equivalent thicknesses of the ferromagnetic layer and sharply worsens its magnetosensitivity. Thus, in the case of a homogeneous magnetic layer, the thickness of which is equivalent to the total thickness of the magnetic phase of a nanostructured multiferroic (1000 nm), a significantly lower value of αE = 1.6 V/cm∙Oe is achieved. The totality of the data obtained indicates the validity of using the nanostructuring method when optimizing the properties of film composite multiferroics. A detailed analysis of the dependences αE(p) and αE (LFeNi) together with the results of computer modeling made it possible to determine the main factors influencing the value of αE. In particular, it is shown that an increase in αE is primarily caused by an increase in the total volume of the magnetostrictive phase in the composite, as well as a weakening of the damping effect of the substrate, which occurs with an increase in the number of periods and the thickness of individual sublayers in the structure.

Magnon gap excitations in van der Waals antiferromagnet MnPSe3

Magneto-spectroscopy methods have been employed to study the zero-wavevector magnon excitations in MnPSe3. Experiments carried out as a function of temperature and the applied magnetic field show that two low-energy magnon branches of MnPSe3 in its antiferromagnetic phase are gapped. The observation of two low-energy magnon gaps (at 1.70 ± 0.05 meV and 0.09 ± 0.01 meV) implies that MnPSe3 is a biaxial antiferromagnet. A relatively strong out-of-plane anisotropy imposes the spin alignment to be in-plane whereas the spin directionality within the plane is governed by a factor of 2.5 × 10−3 weaker in-plane anisotropy.

The structural setting and evolution of the Upper Beaver gold–copper deposit, Ontario, Canada

The ca. 2680 Ma Upper Beaver deposit is an Archean intrusion-related gold–copper deposit located in the Abitibi greenstone belt, Ontario. The deposit is associated with the Upper Beaver Intrusive Complex, which was emplaced in the hanging wall of an extensional listric fault rooted in metavolcanic rocks of the ca. 2704–2695 Ma Blake River assemblage. The fault formed during the development of an overlying basin of fluvial metasedimentary and alkalic metavolcanic rocks of the ca. 2679–2669 Ma Timiskaming assemblage. The Upper Beaver deposit was subsequently rotated to its current position during the formation of a post-Timiskaming fold, the Spectacle Lakes Anticline, associated with the development of the Larder Lake–Cadillac deformation zone, located 7 km south of the deposit. The Upper Beaver deposit is overprinted by the axial planar cleavage of the anticline but is less deformed than other gold deposits located along the deformation zone. Alteration and other pre-existing planar anisotropies enhanced strain partitioning and the development of folds and fabrics in strained mineralized zones of the deposit. Steeply dipping, sericite-altered mineralized zones developed a continuous foliation surrounding boudinaged and recrystallized quartz–calcite–anhydrite veins, whereas strong, shallowly dipping, stratiform, and skarnoid mineralized zones developed a wavy disjunctive cleavage and deformed mainly by folding. The mineralized zones acted as pre-existing anisotropies during deformation and their orientation and composition were key factors in the development of structures at the Upper Beaver deposit, which can be used as a guide for interpreting the development of structures in similar but more complexly deformed deposits along major deformation zones.

Evolution of microstructure, texture and formability of Al–Mg–Si alloys at different hot rolling finish temperatures

The impact of hot rolling finish temperature (HRFT) on the evolution of microstructure, texture, as well as formability—including deep drawability and bendability—of Al–Mg–Si alloy was studied in present work. The obtained results reveal that HRFT has a notable influence on the dynamic softening and dynamic precipitation behaviors during the hot rolling process of the investigated alloy. This leads to the volume fraction and number density of micro-sized Mg2Si particles increase as the increase of HRFT, those of nano-sized particles decrease, and the dislocation density decrease, in the hot-rolled sheets. These microstructural variations persist in the cold-rolled sheets, subsequently affecting the ultimate microstructure, texture, as well as formability of T4P sheets. The deep drawability improves as the HRFT rises, as indicated by the increase in normal anisotropy (r‾) and decrease in planar anisotropy (Δr). This is attributed to the weakening of texture intensity. The bendability, quantified by the minimum hemming factor (Rmin/t), deteriorates as the HRFT rises from 260 °C to 390 °C, attributed to the strengthening of P component along with the weakening of Cube component. Conversely, with the HRFT rises from 390 °C to 420 °C, the bendability improves dramatically due to the significant reduction in the average grain size. A combination of excellent deep drawability and bendability could be obtained by elevating the HRFT to 420 °C, attributed to the combined effect of weakened texture intensity and fine grains.

Spin waves in antiferromagnetically coupled bilayers of transition-metal dichalcogenides with Dzyaloshinskii–Moriya interaction

In this paper we analyse quantized spin waves (also referred to as magnons) in bilayers of two-dimensional van der Waals materials, like Vanadium-based dichalcogenides, VX2 (X = S, Se, Te) and other materials of similar symmetry. We assume that the materials exhibit Dzyaloshinskii–Moriya interaction and in-plane easy-axis magnetic anisotropy due to symmetry breaking induced externally (e.g. by strain, gate voltage, proximity effects to an appropriate substrate/oberlayer, etc.). The considerations are limited to a collinear spin ground state, stabilized by a sufficiently strong in-plane magnetic anisotropy. The theoretical analysis is performed within the general spin wave theory based on the Holstein–Primakoff–Bogoliubov transformation. Accordingly, the description takes into account quantum antiferromagnetic fluctuations. However, it is limited to linear spinwave modes. The Dzyaloshinskii–Moriya interaction is shown to modify the spin wave spectrum of the bilayers, making its low energy part qualitatively similar to the electronic spectrum of the Rashba spin–orbit model.

Grinding- and robotic hammer peening-induced modifications in the near-surface regions of laser-cladded Inconel 718 coatings

Inconel 718 coatings deposited by laser-cladding (LC) on low-alloy steel substrate have been grinded followed by robotic hammer peening (RHP). White layer consisted of nanograins, smaller than 100 nm, has been observed on the surface accompanied with a deformation layer underneath after grinding and RHP. By increasing the RHP intensity (i.e., both the impact energy and the dent overlap), the residual tensile stress measured by X-ray diffraction from the surface of the coating has been monotonically reduced and eventually converted to residual compressive stress with increased in-plane anisotropy, which was accompanied with monotonically increased surface hardening up to 40.5 HRC. Grain deformations have been induced in the white- and deformation-layer, they are dominated by twinning and slipping, respectively. In terms of depth-dependent distributions of low-angle (<15°) grain boundaries and hardening, the effective cold-working thickness induced by the RHP process is over 1000 μm, which is close to the thickness of a single-pass LC deposition. Onset of porosity closures occurred upon the RHP process, especially in the near-surface regions. These findings shed light on integrity enhancement for additive manufacturing of metal alloys by LC-based techniques through introducing interpass RHP process.

Pressure-induced optical anisotropy of HfS2

The effect of pressure on Raman scattering (RS) in bulk HfS2 is investigated under hydrostatic and non-hydrostatic pressure conditions. The RS line shape does not change significantly in the hydrostatic regime up to P = 9.6 GPa, showing a systematic blueshift of the spectral features. In a non-hydrostatic environment, seven peaks appear in the spectrum at P = 7 GPa, which dominate the RS line shape up to P = 10.5 GPa. The change in the RS line shape manifests a pressure-induced phase transition in HfS2. The simultaneous observation of both low-pressure (LP) and high-pressure (HP) related RS peaks suggests the coexistence of two different phases over a wide pressure range. It is found that the HP-related phase is metastable and persists during the decompression cycle down to P = 1.2 GPa, while the LP-related features eventually recover at even lower pressure. The angle-resolved polarized RS performed under P = 7.4 GPa revealed a strong in-plane anisotropy of both the LP-related A1g mode and the HP peaks. The anisotropy is related to the possible distortion of the structure induced by the non-hydrostatic component of the pressure. The results are explained in terms of a distorted Pnma phase as a possible pressure-induced phase of HfS2.

Strong Vertical Piezoelectricity and Broad-pH-Value Photocatalyst in Ferroelastic Y2Se2BrF Monolayer.

With the development of miniaturized devices, there is an increasing demand for 2D multifunctional materials. Six ferroelastic semiconductors, Y2Se2XX' (X, X' = I, Br, Cl, or F; X ≠ X') monolayers, are theoretically predicted here. Their in-plane anisotropic band structure, elastic and piezoelectric properties can be switched by ferroelastic strain. Moderate energy barriers can prevent the undesired ferroelastic switching that minor interferences produce. These monolayers exhibit high carrier mobilities (up to 104 cm2 V-1 s-1) with strong in-plane anisotropy. Furthermore, their wide bandgaps and high potential differences make them broad-pH-value and high-performance photocatalysts at pH value of 0-14. Strikingly, Y2Se2BrF possesses outstanding d33 (d33 = -405.97 pm/V), greatly outperforming CuInP2S6 by 4.26 times. Overall, the nano Y2Se2BrF is a hopeful candidate for multifunctional devices to generate a direct current and achieve solar-free photocatalysis. This work provides a new paradigm for the design of multifunctional energy materials.

Layer-resolved vector magnetometry using generalized magneto-optical ellipsometry

We demonstrate the ability of a single magneto-optical reflection experiment to achieve layer-resolved vector magnetometry in multilayer films. For this purpose, we designed, fabricated, and measured a set of epitaxial ferromagnetic/non-magnetic/ferromagnetic heterostructure multilayer samples that exhibit in-plane uniaxial anisotropy and a tunable ferromagnetic interlayer coupling strength through the non-magnetic interlayer. By means of generalized magneto-optical ellipsometry measurements, we obtain the magnetization angles of the two different ferromagnetic layers independently as a function of the applied field. Hereby, we observe that the magnetization switching of one layer can trigger a discontinuous shift of the magnetization angle in the second layer if ferromagnetic interlayer coupling is present. Moreover, we reproduce the obtained behavior using a model of two coupled macrospins, which corroborates even the unexpected aspects of our experimental results and thus reinforces the sensitivity and reliability of our experimental layer-resolved vector magnetometry.

Polarization-sensitive and wide-spectrum photodetector from ultraviolet to near-infrared light based on 2D tellurium at room temperature

Two-dimensional (2D) materials have emerged as promising candidates for photodetection applications, due to their unique structural and optical properties. Herein, we conducted a comprehensive investigation of the 2D Te-based photodetector. The crystal structure, angle-resolved polarized Raman (ARPR) spectroscopy, and theoretical analysis demonstrate the in-plane lattice anisotropy of Te, underlining its suitability for polarization-dependent photodetection. Photocurrent measurements over a broad spectral range (from 365 to 1310 nm) reveal excellent photoresponse characteristics, with responsivity (Rλ) and detectivity (D*) values reaching up to 1189 A/W and 11.51 × 108 Jones, respectively, under 1064 nm illumination. Furthermore, the Te-based photodetector exhibits superior stability, retaining approximately 90 % of its initial performance after six months of ambient exposure. Polarization-sensitive photodetection experiments show significant dichroism ratios (up to 4.6 for 1064 nm illumination), emphasizing the potential of 2D Te for advanced polarization applications. The combination of the broad spectral response, high anisotropy ratio, and long-term stability positions 2D Te as a promising candidate for future photodetection technologies.

Effects of inserted ultrathin Pt buffer on perpendicular magnetic properties of Ta/TbFeCo/Ta layered structures

We investigated effects of inserted ultrathin Pt buffer on the perpendicular magnetic properties of Ta/TbFeCo/Ta layered structures. For Tb-rich TbFeCo films buffered with Ta and Ta/Pt a compensation thickness is observed at ∼ 6 nm, where the net saturation magnetization vanishes. The perpendicular magnetic anisotropy properties of two structures are found to be governed by a competition of a perpendicular bulk anisotropy and an in-plane interface anisotropy. Compared with Ta-buffered TbFeCo films, the counterparts with insertion of Pt buffer exhibits a larger negative interface anisotropy. A large variation of saturation magnetization and perpendicular magnetic anisotropy with increasing inserted thickness of Pt buffer is observed in the Ta/Pt/TbFeCo/Ta structure. This can be ascribed to the interface-driven variation of exchange interaction between Tb and FeCo at the interface, confirmed by thermomagnetic measurements. A clear correlation between the interface-driven variation of exchange interaction and perpendicular magnetic properties of the TbFeCo films is identified. Our results show the interface plays an important role in the perpendicular magnetic properties of TbFeCo films, which is critical for the application in spintronic devices.

The influence of exchange-bias on the resonance frequencies and damping in IrMn3/[Co/Pt] multilayers

In order to realise single on-chip three axis magnetic field sensing technology without the need for convoluted die stacking, perpendicular media must be exploited. This poses additional challenges in both static-bias and the dynamics of the stack. Presented here are ferromagnetic resonance measurements (FMR) on exchange-biased multilayers of IrMn3/[Co/Pt]n. We chart the evolution of the different anisotropies caused by both magnetic field annealing and increasing repetition number n. The damping of these stacks does not obey the usual symmetry seen in single and bilayer samples with in-plane anisotropy, but instead follows a sin2(θ) dependence. This, we propose, is entirely dominated by spin diffusion from the Co layers into the adjacent heavy metal layers. This is modelled using a simple effective circuit model, providing a guide for the optimisation of complex multilayers.

Anisotropy-free arrayed waveguide gratings on X-cut thin film lithium niobate platform of in-plane anisotropy

Arrayed waveguide grating is a versatile and scalable integrated light dispersion device, which has been widely adopted in various applications, including, optical communications and optical sensing. Recently, thin-film lithium niobate emerges as a promising photonic integration platform, due to its ability of shrinking largely the size of typical lithium niobate based optical devices. This would also enable multifunctional photonic integrated chips on a single lithium niobate substrate. However, due to the intrinsic anisotropy of the material, to build an arrayed waveguide grating on X-cut thin-film lithium niobate has never been successful. Here, a universal strategy to design anisotropy-free dispersive components on a uniaxial in-plane anisotropic photonic integration platform is introduced for the first time. This leads to the first implementation of arrayed waveguide gratings on X-cut thin-film lithium niobate with various configurations and high-performances. The best insertion loss of 2.4 dB and crosstalk of −24.1 dB is obtained for the fabricated arrayed waveguide grating devices. Applications of such arrayed waveguide gratings as a wavelength router and in a wavelength-division multiplexed optical transmission system are also demonstrated.

A criterion for the coalescence of three-dimensional voids

A micromechanics-based yield criterion is developed to model void coalescence of three-dimensional voids under combined tension and shear. The analysis treats a cylindrical cell containing a coaxial cylindrical cavity, both having an elliptic cross section. Limit analysis is employed to first derive a criterion for homothetic cells. The model is then generalized to incorporate independent void spacing ratios (non-homothetic cells) The model predictions are assessed against finite-element based limit analysis on similar geometries. The effects of relative void spacing and void shape on effective yielding are investigated. In tension, the results indicate an increase in the coalescence stress with increasing in-plane anisotropy for both homothetic and non-homothetic cells. The new criterion is chiefly motivated by modeling shear failure. The extent to which the shear limit load reduces when shearing perpendicular to the largest transverse void dimension, as compared with shearing parallel to it, is discussed.

Polarization-dependent electrical transport and thermoelectric properties in (010) surface of λ-Ti3O5

In recent research, the (010) surface of λ-Ti3O5 has demonstrated outstanding capabilities in light absorption and molecular adsorption, promising various applications. In this study, we employed density functional theory (DFT) to analyze the optical and thermoelectric properties of the (010) surface of λ-Ti3O5. Our findings reveal the excellent in-plane anisotropy of the optical anisotropy of bulk λ-Ti3O5 and thermoelectric properties in its (010) surface. The figure of merit (ZT) along the groove structure direction reaches 2.4, while the ZT perpendicular to it is only 0.85. In addition, the electrical transport characteristics along the (010) surface exhibit significant nonlinear characteristics. Our research results indicate that it has the potential to become a favorable material for optical and electronic devices.

THE SIMULATION OF THE ANISOTROPY OF ALUMINUM ALLOY SHEETS BY DEEP DRAWING: A CRUCIAL STUDY FOR THE AUTOMOTIVE AND MATERIALS ENGINEERING INDUSTRIES

Recently, the automotive industry has shown an increasing interest in utilizing thin aluminum alloy sheets to reduce the weight of various car components. The occurrence of uneven cup heights in deep drawing processes is called earing. This issue arises due to the planar anisotropy of sheets, a consequence of crystallographic texture. Therefore, this study involves a meticulously conducted cylindrical cupping test. For the experimental research, four different aluminum alloys were used, each with distinct mechanical and plastic properties. The experimental results of the drawing process were compared with the simulation results using the Simufact Forming software. Different numbers of elements were selected for experimental material with a 1 mm thickness to further compare the simulation results with experiments. In a separate simulation in the Simufact Forming software, the effect of the number of elements on the earing height and computing time was evaluated. The results obtained with five different solvers were compared within Simufact Forming. The results showed significant differences in computing times for the different types of solvers.

Effect of tetragonality on the magnetic preference, elasticity and magnetocrystalline anisotropy of L10-FeM(M = Ni, Pd, Pt) alloys

The effect of tetragonality on the magnetocrystalline anisotropy of L10-FeM(M = Ni, Pd and Pt) ordered alloys is widely concerned, but its effect on other physical properties is not well understood. In this paper, the impact of tetragonality on the magnetic preference, lattice dynamics and elasticity, as well as magnetocrystalline anisotropy of these L10 ordered alloys are systematically investigated based on the first-principles methods. The antiferromagnetic FeNi and FePd alloys are metastable within appropriate axial ratio c/a range, although the ferromagnetic state is ground-state stable. The reduced axial ratio c/a favors the antiferromagnetic state over the ferromagnetic state for the FePt alloy. The tetragonality has a non-monotonic effect on the Young’s modulus and shear modulus, while the bulk modulus is almost tetragonality independent for all L10 ordered alloys. The uniaxial magnetocrystalline anisotropy increases with tetragonality in the fe rromagnetic state, while it shows different trends in the antiferromagnetic state. Interestingly, the antiferromagnetic FePt exhibits planar magnetocrystalline anisotropy in a wide axial ratio c/a range, and a transition between hard magnetic and semi-hard magnetic at c/a = 1.45 is discovered for the FePd alloy. These intriguing properties induced by tetragonality provide us a deeper understanding of the potential rare-earth-free permanent magnet L10 alloys.