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The dynamic mechanical behaviour induced by adiabatic temperature rise of Fe–Mn–Al–C twinning-induced plasticity steel was investigated via the dynamic tensile test and a dynamic constitutive model...

Na-ion solid state batteries operating at room temperature are typically supposed to have a metallic Na anode for sufficiently high energy density. The less known but due to easy processing very promising Na-conducting Na5YSi4O12 glass ceramic is investigated regarding it`s interface resistance in contact with metallic Na electrodes. Two types of this material, with and without P-addition, are investigated. The surface is treated by polishing to induce a defined roughness. Highly polished surfaces lead to incomplete covering with Na metal by application of pressure sufficiently low to avoid the breaking of ceramic. In contrast, surfaces with higher roughness could be covered more homogeneously with Na and thus exhibited significantly reduced interface resistance. These measurements reveal the intrinsically small interface resistance between Na5YSi4O12 glass ceramics and metallic Na, which makes Na5YSi4O12 to promising electrolyte for Na-ion solid state batteries. It is found that prolonged contact of the electrolyte with humid air, like several days or weeks, leads to a strongly increased interface resistance. Thus, storage conditions and surface treatment of the samples after air contact need to be considered carefully.

In order to solve the corrosion and wear of 7050 aluminium alloy (AA7050) caused by the marine environment and prepare excellent coating structure to prolong its service life, the micro-arc oxidati...

The spin-current efficiency in ferromagnet (FM)/nonmagnetic metal (NM) heterostructures is a key issue for many subcategories of spintronics, and it is determined by both the spin Hall angle $({\ensuremath{\theta}}_{\mathrm{SH}})$ of the NM and the spin-mixing conductance $({g}_{\ensuremath{\uparrow}\ensuremath{\downarrow}})$ related to the constituents and, in particular, to the interface. Here, we study spin transport in the ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}(\mathrm{YIG})$/${\mathrm{W}}_{1\text{\ensuremath{-}}x}{\mathrm{Cr}}_{x}$ heterostructure over the full composition by means of the spin Seebeck effect and spin pumping. An appreciably enhanced inverse spin Hall voltage is observed for the substitutional alloy of bcc-$\mathrm{W}$ and $\mathrm{Cr}$, with the maximum obtained at an equiatomic composition. We find that the ${\ensuremath{\theta}}_{\mathrm{SH}}$ of bcc-${\mathrm{W}}_{0.5}{\mathrm{Cr}}_{0.5}$ is 1.3 times as large as that of \ensuremath{\beta}-$\mathrm{W}$, which mainly originates from intensively disordered atomic scattering. More significantly, $\mathrm{YIG}$/bcc-${\mathrm{W}}_{0.5}{\mathrm{Cr}}_{0.5}$ has a ${g}_{\ensuremath{\uparrow}\ensuremath{\downarrow}}$ value of $1.42\phantom{\rule{0.25em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.25em}{0ex}}{10}^{18}\phantom{\rule{0.25em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}$, which is more than twice that for $\mathrm{YIG}$/\ensuremath{\beta}-$\mathrm{W}$ ($5.98\phantom{\rule{0.25em}{0ex}}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0.25em}{0ex}}{10}^{17}\phantom{\rule{0.25em}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}$). Meanwhile, a sizable interfacial electric field is identified in $\mathrm{YIG}$/\ensuremath{\beta}-$\mathrm{W}$, but not in $\mathrm{YIG}$/bcc-${\mathrm{W}}_{0.5}{\mathrm{Cr}}_{0.5}$, showing strong correlation between ${g}_{\ensuremath{\uparrow}\ensuremath{\downarrow}}$ and the interfacial electric field. This work not only provides a readily achievable alloy with ${\ensuremath{\theta}}_{\mathrm{SH}}$ exceeding that of the metastable \ensuremath{\beta}-$\mathrm{W}$, but also implies the possibility of manipulating ${g}_{\ensuremath{\uparrow}\ensuremath{\downarrow}}$ via Rashba-type spin-orbit coupling by engineering an interfacial electric field in insulating FM/NM heterostructures.

The martensite structures and the mechanical properties of the solution treated Ti-16Nb-(0, 0.3, 0.7, 1)Ag (at.%) alloys were systematically investigated. For all the Ti-Nb-Ag alloys, different martensite variants are in { 1 1 1 } type I and 2 1 1 type II twin relation, while the { 1 1 1 } type I twins are the dominant substructures inside a martensite variant. Substructures of the ( 0 1 1 ) compound twins are also observed in the Ti-16Nb-1 A g alloy. With increasing the Ag content, the ultimate tensile strength is improved significantly, while the elastic modulus decreases slightly. As a result, the Ti-16Nb-1 A g alloy has a good combination of high strength (840 Mpa) and low elastic modulus.

The phase transformation mechanism leading to the formation of intragranular α precipitates in Ti−16Nb (at.%) alloy was investigated by TEM. Spinodal decomposition of the β matrix acts as the uniformly distributed heterogeneous nucleation sites for such α precipitates upon annealing at 550 °C. An α-like atomic arrangement with severe lattice distortion forms in the bcc lattice at the early stage of phase transformation and it transforms to the perfect hcp atomic structure gradually in a displacive mode.

Ti-Ta-Zr thin films are considered to be promising high-temperature shape memory materials with operation temperature above 100 °C. The effects of annealing treatment on microstructure and shape memory behavior of Ti-Ta-Zr thin films were investigated. The Ti-Ta-Zr thin films under different annealing conditions were all turned out to be α″ phase at room temperature while the microstructures were distinct. The shape memory effect increased with the decreasing of annealing temperature with the maximum shape memory recovery rate of 65% after annealing at 550 °C for 2 min. When the grain size is 8 nm, shape memory effect disappeared.

Rare-earth iron garnet films with perpendicular magnetic anisotropy (PMA) are important to develop magnon-based spintronic devices. In this study, high quality epitaxial Ho3Fe5O12 (HoIG) films with PMA are fabricated on (111) Y3(Sc2Ga3)O12 substrates by sputtering. The magnetization compensation temperature of HoIG films is determined to be 130 K, highly consistent with its bulk value. The magnetic dead layer at the interface is quantified as thin as about 0.6 nm through polarized neutron reflectivity. Furthermore, spin–orbit torque switching in HoIG/Pt films is realized with the threshold current density of 1.4 × 1011 A/m2 and assisting field as small as 10 Oe. These results provide one more alternative for spintronic materials using compensated ferrimagnetic insulators.

A new method, called Cloud of Points (COP) Reconstruction, is proposed in the present work to extend the meshfree method to simulate viscous flows. With the characters of viscous flows, the anisotropic COP structure is distributed in boundary layer. The proposed method can improve the anisotropic COP structure to isotropic COP structure and reduce the condition number of the least square coefficient matrix for conventional meshfree method. The values of the new reconstructed points are calculated by the Lagrange interpolation. The accuracy and the robustness of the presented meshfree solver are demonstrated on a number of standard test cases, including the functions with analytical gradients and the viscous flows past NACA0012 airfoil. The comparison of the simulation results with the experimental data and other numerical simulation data are also investigated.

This paper reports the martensitic transformation of NiMnGa film induced by proton irradiation, which is of great significance for evaluating the reliability of NiMnGa film. Ni-Mn-Ga thin films are spotlighted as next-generation alternatives to currently used micro-actuators in the MEMS system for aircraft. Nonetheless, their potential applications are hindered by the stability under proton irradiation in the space. In the present manuscript, the microstructure evolutions of Ni50Mn25Ga25 thin films are investigated under various proton irradiation doses. A large number of point defects are introduced into the thin films at the irradiation dose over 1 × 1016 p/cm2 as indicated by the positron annihilation spectrum. And the type of defects remains the same after irradiation Consequently, 7 M martensite is formed on the surface of austenitic Ni50Mn25Ga25 thin films driven by the internal stress filed based on the GI-XRD and TEM observations.

Magnetic damping of the free layer of CoFeB in the spin valve IrMn/CoFe/Cu/CoFeB with large exchange bias has been characterized by frequency-swept ferromagnetic resonance under a series of fixed magnetic fields. The damping constant shows little difference between the parallel and antiparallel magnetization configurations, consistent with the theoretical prediction. Remarkably, in the intermediate states of the pinned CoFe layer under reversal, the effective damping constant of the CoFeB layer is significantly enhanced from 0.0119 up to 0.0292. This enhancement, exceeding the effect of the pumped spin current appreciably, is mainly due to the inhomogeneous broadening and/or two-magnon scattering caused by the stray field emerging from the domain walls (DW) of the pinned CoFe layer when its magnetization is partially reversed. Meanwhile, a resonance frequency shift is also observed in the presence of DW. Our result confirms the strong influence of the pinned layer DW on the magnetic damping in spin valves, which should be properly excluded while dealing with the nonlocal spin-transport-induced damping in heterostructures.

Based on Q345 steel, high-strength low-alloy surfacing layers with Nb content ranging from 0.0041 to 0.26 wt-% were prepared by adding Nb element into electrode coating and manual electric arc welding, the microstructure as well as mechanical properties of surfacing layers were evaluated and analysed. The experimental results show that with the increasing of Nb content, the grain size becomes smaller meanwhile the microstructure distribution is more uniform, the size of hard phase martensite/austenite gradually decreases and the NbC precipitates increases. The yield and tensile strength greatly increase for the fine-grain strengthening of Nb and the precipitation strengthening of NbC, moreover, the impact toughness is significantly improved due to the microstructure variation and obvious grain refinement.

The temperature memory effect (TME) has been investigated in Ti 49.5 Ni 34.5 Cu 11.5 Pd 4.5 alloy with a narrow hysteresis. The TME can be enhanced through multiple partial thermal cycling (TME training). The TME obtained by training is repeatable and hard to wipe out, which can be detected even after 1000 following complete thermal cycles. A difference in the dislocation density between different martensite regions is introduced during training, which results in the TME. It increases with increasing training cycles, and graduates away slowly because of the rare introduced dislocations during the following complete thermal cycles, leading to the repeatable TME.

The effects of thermomechanical treatment on microstructure, mechanical properties and shape memory effect of Ti–13V–3Al alloy were investigated. A dual-phase structure which consists of α phase and α″ martensite phase forms after thermomechanical treatment. As annealing temperature increases, the amount of α phase decreases and its morphology changes. Stress plateau decreases when annealing temperature increases and elongation shows the opposite trend. Ti–13V–3Al alloy annealed at 700 °C has the best comprehensive mechanical property. Recoverable strain first increases then decreases as annealing temperature increases. Ti–13V–3Al alloy annealed at 700 °C for 0.5 h displays a large fully recoverable strain of 7.5%. It is believed that small, uniformly distributed α phase benefits the shape memory effect. With the help of α phase, martensite variants become small. The variants are supposed to have a good mobility and that reduces the chance of introducing irrecoverable strain during tensile test. The microstructure evolution of Ti–13V–3Al alloy annealed at 700 °C during deformation was investigated. When the pre-strain is less than 7.5%, the recoverable martensite reorientation process contributes to the deformation. When the pre-strain exceeds 7.5%, the crossover of martensite plates leads to the deterioration of shape memory effect.

The effects of indium on the microstructure, transformation temperature, mechanical properties, and shape memory effect of (Ti83Ta17)85−xZr15Inx alloys were investigated. The results showed that (Ti83Ta17)85−xZr15Inx (x = 1, 3, 5)(at%) alloys were all composed of orthorhombic α"-martensitic phase. The reverse martensitic transformation starting temperature (As) was 346 °C for x = 1 and increased with increasing indium content. The Young's modulus firstly decrease then increase with the addition of Indium. When the Indium content is 1 at%, the lowest strength and the largest elongation 25.8% can be obtained. The minor addition of indium can make up for the deficiency of low plasticity and retained a relatively large shape memory recovery strain. A prefect recovery strain of 4% were obtained in all (Ti83Ta17)85−xZr15Inx alloys.

${\mathrm{Y}}_{3}\mathrm{F}{\mathrm{e}}_{5}{\mathrm{O}}_{12}$ (YIG) is known for its long magnon diffusion length. Although it has the known lowest damping rate, an even longer diffusion distance is still highly desired since it may lead to a much more efficient information transmission and processing. While most of previous works focused on the generation and detection of magnons in YIG, here we demonstrate how to depress the damping rate during the diffusion of magnon. By selectively exciting the spin state transition of the Fe ions in YIG, we successfully increase magnon diffusion length by one order of magnitude, i.e., from the previous reported \ensuremath{\sim}10 \ensuremath{\mu}m up to \ensuremath{\sim}156 \ensuremath{\mu}m (for the sample prepared by liquid phase epitaxy) and \ensuremath{\sim}180 \ensuremath{\mu}m (for the sample prepared by pulsed laser deposition) at room temperature. The diffusion length, determined by nonlocal geometry, is \ensuremath{\sim}30 \ensuremath{\mu}m for the magnons induced by visible light and above 150 \ensuremath{\mu}m for the laser of 980 nm. In addition to thermal gradient, light excitation affects the electron configuration of the $\mathrm{F}{\mathrm{e}}^{3+}$ ion in YIG. Long-wavelength laser is more effective since it causes a transition of the $\mathrm{F}{\mathrm{e}}^{3+}$ ions in $\mathrm{Fe}{\mathrm{O}}_{6}$ octahedron from a high spin to a low spin state and thus causes a magnon softening which favors a long-distance diffusion. The present work paves the way toward an efficient tuning of magnon transport which is crucially important for magnon spintronics.

After 5000 thermal cycles, the change of the transformation temperature is less than 1 °C in a Ti 50.5 Ni 33.5 Cu 11.5 Pd 4.5 alloy. Also, the hysteresis becomes smaller nearing zero. Using thermal dynamic calculations, the elastic energy is nearly unchanged during the thermal cycles, which means there is little addition of the irreversible energy. The transmission electron microscopy observations show that the irreversible defects such as dislocations are rare in the reciprocating phase transition processes. Both of these explain the high thermal stability mechanism.

The effects of Al content on martensitic transformation and shape memory effect of Ti–V–Al alloys were investigated. The addition of Al suppressed the formation of ω phase and improved the shape memory effect and mechanical properties. The optimal Al content for getting a high martensitic transformation temperature and a good shape memory effect is determined to be 3 at.%. The recoverable strain with 6% pre-strain was 4.2% and the martensitic transformation temperature of Ti–13V–3Al was 359 °C. The alloy showed an elongation of over 20%.

The Mn 53 Ni 25 Ga 22 ferromagnetic shape memory alloy has been aged at various temperatures for 3 h, and the martensitic transformation and magnetic properties have been investigated by differential scanning calorimetry (DSC) and the Physical Property Measurements System (PPMS, Quantum Design). The results show that precipitation has an obvious effect on martensitic transformation temperatures, Curie temperatures and saturation magnetization. Aging greatly affects transformation temperatures due to modified composition of the matrix. Martensitic transformation temperature, Curie temperatures first decreased and then increased with increase of aging temperature, reaching their minimum values at the aging temperature of 773 K. The saturation magnetizations first rapidly increase and then rapidly decrease with increase of aging temperature, reaching the maximum value at 773 K. It can be concluded that appropriate ageing treatment can enhance the saturation magnetization of Mn 53 Ni 25 Ga 22 alloy.

Most magnetic refrigeration materials showing a large and reversible magnetocaloric effect (MCE) undergo a second-order ferromagnetic (FM) transition involving large-moment magnetic species on one sublattice. A stronger MCE is expected near a cooperative FM order of two or more magnetic species with large magnetic moments residing on different sublattices, but experimental realizations are rare. Here we report on the discovery of large MCE in the cubic pyrochlore $\mathrm{E}{\mathrm{r}}_{2}\mathrm{M}{\mathrm{n}}_{2}{\mathrm{O}}_{7}$ near its second-order FM transition at ${T}_{c}\ensuremath{\approx}34\phantom{\rule{0.16em}{0ex}}\mathrm{K}$; under the magnetic field change of 1 and 5 T, the maximum magnetic entropy change $\ensuremath{-}\mathrm{\ensuremath{\Delta}}{S}_{M}$ is 5.27 and $16.1\phantom{\rule{0.16em}{0ex}}\mathrm{J}\phantom{\rule{0.16em}{0ex}}\mathrm{k}{\mathrm{g}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$, and the estimated magnetic refrigerant capacity reaches 68 and $522\mathrm{J}\phantom{\rule{0.16em}{0ex}}\mathrm{k}{\mathrm{g}}^{\ensuremath{-}1}$, respectively. These latter values are among the largest for the known MCE materials. The observed giant and reversible MCE in $\mathrm{E}{\mathrm{r}}_{2}\mathrm{M}{\mathrm{n}}_{2}{\mathrm{O}}_{7}$ is mainly attributed to the large saturation moment of $18.9\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{\mathrm{B}}$ per formula unit owing to a simultaneous FM ordering of the rear-earth ${\mathrm{Er}}^{3+}$ and transition-metal ${\mathrm{Mn}}^{4+}$ localized moments. Our results suggest that $\mathrm{E}{\mathrm{r}}_{2}\mathrm{M}{\mathrm{n}}_{2}{\mathrm{O}}_{7}$ pyrochlore is a promising candidate for magnetic refrigeration applications in the temperature range 20--80 K. More importantly, this work provides a new material system for developing high-performance MCE materials that can exhibit a strongly coupled FM transition involving two magnetic sublattices of large local moments in a single-phase material.

Under a perpendicular temperature gradient, a heterostructure of ferromagnetic insulator plus normal metal yields a voltage via the inverse spin Hall effect (ISHE). When a $f\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}g\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c$ metal is used instead, though, it becomes tricky to evaluate the ISHE voltage. In systems with large spin-orbit interaction, the authors observe significantly enhanced ISHE signals, suggesting that exchange-bias structures can be effective for detecting spin currents. This study provides insight into engineering hybrid spintronic devices to generate, manipulate, and detect pure spin current.

A novel method combining experimental test and heat transfer modeling was developed to determine the thermal contact conductance (TCC) between thin metal sheets as a function of contact pressures. In the experiment, thin metal samples were sandwiched between one white light transparent and one infrared (IR) transparent glass disks pressed together under different pressure levels. The metal stack was then heated up from the white light transparent side by an intense short pulse of flash light. The temperature transient on the other side was measured by an IR camera. To obtain a value of TCC, two separate experiments having different layers of thin sheet materials were performed and the values of maximum temperature rise were measured. Numerical heat transfer modeling was used to calculate the temperature evolution in the stack-up comprised of metal layers sandwiched between two glass disks. The heat transfer calculation results showed that TCC had a strong correlation to the ratio of maximum temperature rise between the two experiment configurations, but it was insensitive to the variations of other thermal properties. Thus, for a given pair of metal sheets in contact, a unique correlation between the TCC and the ratio of temperature rise was established using the heat transfer calculation. Such correlation allows the direct determination of the TCC value from the ratio of the experimentally measured temperature rise. The TCC between three types of thin metal sheets (i.e., 0.2-mm-thick Al, 0.2-mm-thick Cu and 0.9-mm-thick Cu) were measured and compared with the available literature data.

The effects of aging on martensitic transformation, thermoelastic and fracture behavior were investigated in the Mn 53 Ni 25 Ga 22 ferromagnetic shape memory alloy. The results show that precipitation has obvious effects on the phase transformation behavior and fracture behavior. The transformation temperature gradually decreases and then increases when the samples are aged at increasing temperatures, reaching the minimum value at an aging temperature of 773 K for 3 h, which is mainly attributable to elemental diffusion between the matrix and the precipitate. The enthalpy and entropy changes rapidly increase and then gradually decrease with an increase in the aging temperature, reaching their minimum values at an aging temperature of 573 K. Moreover, the brittleness, low strength and poor processability of Mn–Ni–Ga alloys greatly limit their application. We attempted to improve the mechanical properties without sacrificing the magnetic and thermoelastic properties by using appropriate aging treatments. The highest compressive strength and compression strain of 1594 MPa and 20.3% were obtained in alloys aged at 673 K and 573 K for 3 h, respectively. These values are approximately 750 MPa and 8% higher than the solution-treated Mn 53 Ni 25 Ga 22 alloy. As a result, the improvements in the mechanical properties of Mn 53 Ni 25 Ga 22 alloys from the aging treatments are mainly due to changes in the fracture type from intergranular brittleness to a quasi-cleavage ductile fracture. By controlling the number and the size of the precipitates and aging at a temperature no higher than 773 K for no more than 3 h, a significant improvement in the compressive strength and ductility of the alloys can be expected through the fine-tuning of the small precipitates.

The role of relative potential energy of occupied sites in high-order harmonic generation from solid states is investigated. It is found that the conversion efficiency of high-order harmonic spectrum can be enhanced by tuning the relative potential energy of neighboring occupied sites in one-dimensional model. This phenomenon can be attributed to the changing of energy bands. A two-dimensional Kronig–Penney potential is applied to model the salt–rock structure. Similar phenomenon as in the one-dimensional case is also found. Our results provide a potential method to enhance the efficiency of high-order harmonic generation from solids.

Nanometer-thick Y3Fe5O12 (YIG) films epitaxially grown on (111) Gd3Ga5O12 with a magnetic dead layer as thin as about 1.2 nm are quantified by polarized neutron reflectivity and magnetization measurements. Vacuum annealing on YIG at 300–400 °C leads to substantial reduction in the anomalous Hall effect, spin Hall magnetoresistance, and spin pumping in YIG/Pt bilayers but causes large enhancement in the spin Seebeck effect. The structural, static, and dynamic magnetic measurements show that the annealing has no discernible influence on the global oxidization states and saturation magnetization of YIG films but introduces subtle defects possibly in the form of oxygen vacancies. This study suggests that subtle defects in thin YIG films have multiple effects on the spin transport properties, and caution should be taken in annealing YIG in vacuum.

High quality epitaxial (111) Y3Fe5O12 (YIG) films are fabricated by annealing amorphous precursor films that are sputtering deposited on three kinds of single crystal garnet substrates with lattice constants exceeding that of YIG by a ratio from 0.76% to 1.58%. The effective perpendicular magnetic anisotropy (PMA) in the YIG films is significantly altered by the epitaxial strain induced magnetoelastic anisotropy. Large PMA is demonstrated in the fully strained thin YIG films on substrates with lattice mismatch from 1.05% to 1.58% due to the overwhelming of the magnetoelastic anisotropy. Less-strained YIG films, corresponding to partial strain relaxation at larger YIG thickness or smaller substrate lattice mismatch at 0.76%, show substantial but insufficient magnetoelastic anisotropy to overcome shape anisotropy. Magnetotransport characterization on YIG/Pt bilayers shows that the surface of YIG with either in-plane or perpendicular magnetization allows efficient equilibrium and/or nonequilibrium spin interexchange across the heterostructure interface.

A Heusler Ni50Mn29Ga20Gd1 ferromagnetic shape memory alloy is obtained by substituting 1 at-%Gd for Ga in a ternary Ni50Mn29Ga21 alloy. The microstructure, phase transformation, magnetic and mechanical properties of Ni50Mn29Ga20Gd1 alloy are investigated. It is shown that the Ni50Mn29Ga20Gd1 alloy has the best overall mechanical properties among the Ni50Mn29Ga21-xGdx (x = 0, 0·1, 0·5, 1, 2, 5) alloys. Compression tests show that a compressive strength of 1124·42 MPa with a compressive strain up to 16·25% can be achieved in this alloy. The mechanism of the improved mechanical properties is also discussed. The results demonstrate that the grains are refined obviously by the addition of 1 at-% Gd. The microstructure of the Ni50Mn29Ga20Gd1 alloy consists of the matrix and the hexagonal Gd(Ni, Mn)4Ga phase distributing mainly along the grain boundaries. Martensitic structure changes from five-layered martensite with 0 at-%Gd to seven-layered modulated martensite with 1 at-%Gd. One-step thermoelastic ma...

The effect of Zr content on the thermal stability of martensite transformation and the shape memory effect of Ti–Ta alloy was investigated. Zr addition improved the thermal stability and shape memory effects of Ti–Ta alloys. Ti–20Ta–10Zr alloy exhibited good thermal stability with a peak martensite reverse transformation temperature of 763 K and a recovered strain of 4.6% with 8% pre-strain.

Charged polar interfaces such as charged ferroelectric walls or heterostructured interfaces of ZnO/(Zn,Mg)O and LaAlO3/SrTiO3, across which the normal component of electric polarization changes suddenly, can host large two-dimensional conduction. Charged ferroelectric walls, which are energetically unfavourable in general, were found to be mysteriously abundant in hybrid improper ferroelectric (Ca,Sr)3Ti2O7 crystals. From the exploration of antiphase boundaries in bilayer-perovskites, here we discover that each of four polarization-direction states is degenerate with two antiphase domains, and these eight structural variants form a Z4 × Z2 domain structure with Z3 vortices and five distinct types of domain walls, whose topology is directly relevant to the presence of abundant charged walls. We also discover a zipper-like nature of antiphase boundaries, which are the reversible creation/annihilation centres of pairs of two types of ferroelectric walls (and also Z3-vortex pairs) in 90° and 180° polarization switching. Our results demonstrate the unexpectedly rich nature of hybrid improper ferroelectricity., Charged ferroelectric domain walls show promise for two-dimensional conduction, but their abundance within (Ca,Sr)3Ti2O7 crystals is poorly understood. Here, Huang et al. discover topology related domain structures in such materials, which reveal the rich nature of hybrid improper ferroelectricity.

Spin Hall angle, which denotes the conversion efficiency between spin and charge current, is a key parameter in the pure spin current phenomenon. The search for materials with large spin Hall angle is indeed important for scientific interest and potential application in spintronics. Here the large enhanced spin Hall effect (SHE) of Au-Cu alloy is reported by investigating the spin Seebeck effect, spin Hall anomalous Hall effect, and spin Hall magnetoresistance of the ${\mathrm{Y}}_{3}\mathrm{F}{\mathrm{e}}_{5}{\mathrm{O}}_{12}$ (YIG)/$\mathrm{A}{\mathrm{u}}_{x}\mathrm{C}{\mathrm{u}}_{1\ensuremath{-}x}$ hybrid structure over the full composition. At the near equiatomic Au-Cu composition with maximum atomic disorder scattering, the spin Hall angle of the Au-Cu alloy increases by two to three times together with a moderate spin diffusion length in comparison with Au. The longitudinal spin Seebeck voltage and the spin Hall magnetoresistance ratio also increase by two to three times. More importantly, no evidence of anomalous Hall effect is observed in all YIG/Au-Cu samples, in contrast to the cases of other giant SHE materials Pt(Pd), Ta, and W. This behavior makes Au-Cu free from any suspicion of the magnetic proximity effect involved in the hybrid structure, and thus the Au-Cu alloy can be an ideal material for pure spin current study.

EMCD (electron magnetic circular dichroism) technique opens a new door to explore magnetic properties by transmitted electrons. The recently developed site-specific EMCD technique makes it possible to obtain rich magnetic information from the Fe atoms sited at nonequivalent crystallographic planes in NiFe2O4, however it is based on a critical demand for the crystallographic structure of the testing sample. Here, we have further improved and tested the method for quantitative site-specific magnetic measurement applicable for more complex crystallographic structure by using the effective dynamical diffraction effects (general routine for selecting proper diffraction conditions, making use of the asymmetry of dynamical diffraction for design of experimental geometry and quantitative measurement, etc) and taken yttrium iron garnet (Y3Fe5O12, YIG) with more complex crystallographic structure as an example to demonstrate its applicability. As a result, the intrinsic magnetic circular dichroism signals, spin and orbital magnetic moment of iron with site-specific are quantitatively determined. The method will further promote the development of quantitative magnetic measurement with high spatial resolution by transmitted electrons.

A Heusler Ni 50 Mn 30 Ga 1 Cu 4 alloy with the highest compressive strength has been obtained by substituting 4 at% Cu for Ga in a ternary Ni 50 Mn 30 Ga 20 ferromagnetic shape memory alloy. It is shown that the highest compressive strength of 3178.9 MPa with a fracture strain up to 13.6% can be achieved at room temperature. To date, this is the highest compressive strength reported in the Ni–Mn–Ga alloy system. The martensitic structure changes from 7M with 0 at% Cu to non-modulated T martensite with 4 at% Cu . In addition, the Cu doping markedly increases the martensitic transformation temperature from 82.1 °C to 136.6 °C. At the same time, the Curie temperature and saturation magnetization for the Ni 50 Mn 30 Ga 16 Cu 4 alloy slowly decrease due to the 4 at% Cu addition.

A Heusler Ni45·4Mn39·5In13·1Gd2 alloy with high transformation temperature has been obtained by substituting 2 at-%Gd for Mn in a ternary Ni45·4Mn41·5In13·1 ferromagnetic shape memory alloy. It is shown that the microstructure of Ni45·4Mn39·5In13·1Gd2 alloy consists of a matrix and a Gd rich phase. The Ni45·4Mn39·5In13·1Gd2 alloy exhibits a martensitic transformation start temperature of 726 K, and the transformation hysteresis is Af−Ms = 148°C. At room temperature, non-modulated martensite of tetragonal L10 structure is observed in Ni45·4Mn39·5In13·1Gd2 alloy. In addition, it is revealed that the addition of Gd significantly enhances the compressive strength and improves the ductility of Ni45·4Mn39·5In13·1Gd2 alloy.

A slight decrease in average friction coefficient and a great decline in volume loss (reaching to 63.1%) have been obtained from TiNi matrix composites prepared by sintering 1 vol.% multi-walled carbon nanotubes (MWCNTs) with Ti and Ni elemental powders. It is considered that in situ TiC and the remaining MWCNTs act as reinforcements and plays the major role in the improvement. This study explores the possibility of developing novel TiNi matrix tribocomposites.

The boron-doped SnO2 (BTO) films were prepared by spray pyrolysis. The XRD results shows the preferred orientation of the BTO films changes from plane (110) to (101) as the increasing of boron concentration in SnO2, which further leads to the variation of grains shape on the surfaces. The FTIR and Hall-Effect results indicate the solution process: the boron ions prefer to occupy the interstitial site in SnO2 lattice, which play the role of donor of free electrons; while beyond a certain boron concentration, boron ions start to replace the tin ions of lattice, which has a negative effect on carrier concentration. The scattering mechanism of BTO is also discussed in the paper based on the grain size and meal free path.

The fluorine-doped tin oxide films (FTO) were prepared with SnCl2 and SnCl4 precursors using the spray pyrolysis method. The vibrational feature of oxygen vacancy in FTIR has been identified. The oxygen vacancy plays a role of donor in FTO films, although it becomes inconspicuous with an increase in fluorine concentration in the solution. The substitution of fluorine for oxygen has also been confirmed by FTIR spectrum, and it further indicates the production of fluorine doping is α-SnF2. The reflectivity shows a close relation with the carrier concentration, suggested by the Drude theory. The discussion of scattering mechanism in FTO films suggests that impurity ions are the main scattering centers for free carriers.

The comprehensive three-dimensional mathematical model proposed in Part 1 is used to investigate the effect of rotating electromagnetic stirring on the solidification process of copper hollow bille...

A thermal–mechanical coupled model has been employed to simulate the temperature and strain–stress fields of continuous casting steel billets with ANSYSTM software. In the model, a gap dependent heat transfer condition was introduced to modify the function of heat flux between mould wall and billet surface. The thermal and mechanical properties of materials as well as yield function were used considering the effect of temperature. The shrinkage behaviours of four round billets which solidified within four different petal-like moulds were studied by indirect coupled method. The simulation results showed that the six-petal mould is the best one in the four optional moulds. According to the evolution of shrinkage and the principle of compensating, a petal-like inner cavity and excessive taper were designed for continuous casting of round steel billets. The designed mould was tested in steel factory, which was equivalent or even better than the existing advanced moulds in terms of the surface and inner qualities of billets.

The effects of Sn addition on phase transformation behavior and magnetocaloric properties of Mn50Ni25Ga25−xSnx (x=0, 0.1, 0.5, 1 and 2 at%) alloys were investigated in this work. The results show that the addition of Sn reduces the structural transformation temperatures. It is found that the second phase exists in the austenite matrix of the as-casted alloys at room temperature. After being annealed at 1073 K for 48 h, the precipitates totally soluted into the matrix. Magnetization measurements indicate that the saturation magnetizations of the alloys increase significantly with increase in Sn contents. In addition, the ΔM/ΔS obviously increases with increase in the Sn contents, implying the higher efficiency shift of the martensitic transformation temperature under the magnetic field.

Ni–Mn–Ga thin films have been fabricated by using magnetron sputtering technique under various substrate negative bias voltages. The effect of substrate negative bias voltage on the compositions and surface morphology of Ni–Mn–Ga thin films was systematically investigated by energy dispersive X-ray spectrum and atomic force microscopy, respectively. The results show that the Ni contents of the thin films increase with the increase of the substrate negative bias voltages, whereas the Mn contents and Ga contents decrease with the increase of substrate negative bias voltages. It was also found that the surface roughness and average particle size of the thin films remarkably decrease with the increase of substrate negative bias voltages. Based on the influence of bias voltages on film compositions, a Ni 56 Mn 27 Ga 17 thin film was obtained at the substrate negative bias voltage of 30 V. Further investigations indicate that the martensitic transformation start temperature of this film is up to 584 K, much higher than room temperature, and the film has a non-modulated tetragonal martensitic structure at room temperature. Transmission electron microscopy observations reveal that microstructure of the thin film exhibits an internally (1 1 1) type twinned substructure. The fabrication of Ni 56 Mn 27 Ga 17 high-temperature shape memory alloy thin film will contribute to the successful development of microactuators.

The effects of aging on magnetic properties and phase transformation were investigated for Ni 53 Mn 23.5 Ga 23 Ti 0.5 shape memory alloy. The results show that the amount and size of Ni 3 Ti particles firstly increase and then amount of second phase decreases with the increasing aging temperature. Moreover, the transformation temperatures gradually decrease; Curie temperatures slightly decrease first and reach their minimum values at 973 K then increase with the increasing aging temperature. The saturation magnetizations firstly remain almost unchanged and then slightly decrease when aging temperature is above 973 K.

The effects of electromagnetic brake (EMBR) on the flow of liquid melt during continuous casting of cladding aluminium alloys are investigated by numerical simulation and validated by experiments. The results show that the EMBR can effectively damp the strong impingement of the two streams of melt, decrease the jet length and reduce the recirculation zone in the centre of the mould. When the casting speed is 200 mm min−1, a 0·15 T direct current magnetic field can effectively constrain the mixing of different alloys in the molten pool. According to the parameters suggested by simulation, the cladding billet of Al–Si and Al–Mg alloys is successfully produced.

The effects of aging on martensitic transformation and microhardness were investigated for Ni53Mn23·5Ga18·5Ti5 ferromagnetic shape memory alloy. The results show that precipitation has obvious effect on martensitic transformation temperature and the microhardness increases with increasing aging temperature up to 973 K, and then decreases gradually with the further increase in aging temperature.

The Ti 49 Ni 46.5 Ce 4.5 alloy thin film was prepared by direct current (DC) magnetron sputtering system for the first time. Crystallization kinetics, phase composition and the behaviors of martensitic transformation were studied. The results by X-ray diffraction (XRD) and differential scanning calorimeter (DSC) demonstrated that the primary second phase of TiNiCe alloy thin films was Ce 2 Ni 7 phase, apparent activation energy was determined to be 510 kJ/mol at the continuous heating process, Avrami exponents for different isothermal temperature were in the range of 1.1–1.88 between 713 and 730 K, one-step martensitic transformation was observed in the crystallized Ti 49 Ni 46.5 Ce 4.5 alloy thin films. The influence of thermal process on martensitic transformation temperature was investigated with non-isothermal and isothermal crystallization. The reason behind the transformation temperature change was also discussed.

The Ti36Ni41Hf15Cu8 melt-spun ribbon undergoes a B2 ↔ B19′ transformation upon cooling and heating. When the Ti36Ni41Hf15Cu8 melt-spun ribbon is annealed at 873 K for 1 h, the spherical (Ti, Hf)2Ni particles with a diameter of 20–40 nm precipitate in the grain interior. The fine (Ti, Hf)2Ni precipitates improve the stability of phase transformation temperatures and cause martensite domains, with (001) compound twins in three orientations dominant instead of (011) type I twins. {111}-, {113}- and (001)//{111}-type boundaries are observed among these martensite domains. When the (Ti,Hf)2Ni precipitates coarsen, (011) type I twins become main martensite structures in the ribbon annealed at 973 K for 1 h.

In this paper, the phase transformation behaviors and structures of Ni 50 Mn 28 + x Ga 22 − x ( x = 0, 1, 2, 3) alloys and ribbons as well as the magnetic properties of ribbons are discussed. Rapidly quenching process decreases the degree of order and introduces some internal stress, which influences the martensitic transformation temperatures of the ribbons. The structures of the ribbons become 7 M modulated, which is different from the 5 M modulated martensite of the corresponding bulk materials. Higher annealing temperature and annealing under magnetic field are all in favor of the magnetization of the ribbons, and this is related to the enhancement of orientation perpendicular to the surface of the ribbons.

The influence of Co on the microstructure, phase transformation temperature, mechanical properties and shape memory effect of TiNiNb alloys has been investigated by X-ray diffraction, differential scanning calorimetry, tensile stress–strain measurements and bending tests, respectively. The results show that the addition of Co suppresses the brittle (Ti,Nb) 2 Ni phase of NiTiNb alloys, and the phase transformation temperature and lattice parameter of Ni 46.5− x Ti 44.5 Nb 9 Co x alloys are decreased with the increase of Co content. The yield strength of NiTiNb alloys has been improved due to the addition of Co. In particular, Ni 45.5 Ti 44.5 Nb 9 Co 1 alloy exhibits highest yield strength among the Ni 46.5− x Ti 44.5 Nb 9 Co x (Co = 0.5, 1, 1.5, 2) alloys, and a maximum completely recoverable strain of 7.8% has been achieved.