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The influence of high magnetic field annealing on the morphology, microstructure, and properties of pulsed-electrodeposited Co-Ni-P films was investigated. The as-deposited film with a rough surface changed into uniform nanocrystalline during the magnetic field annealing process. In particular, the formation of intestine-like appearance with spherical clusters vanishing is favored from a moderate magnetic field strength of 6 T, due to the polarized effects. Meantime, the diffraction peak (111) of α (fcc) phase shifts to the right direction, which is attributed to the fact that more Co atoms from phosphide phase are incorporated into the Ni lattice, in comparison with the case of annealing under 0 T and 12 T magnetic fields. The mechanical and magnetic properties of the films reach relative optimum values at B=6 T. The evolution of magneto-induced modification in the Co-Ni-P morphology, structure, and properties can be explained by the polarized effect and the diffusion-acceleration effect under a high magnetic field. [ABSTRACT FROM AUTHOR]

Several samples of Zn-Sb alloys, composed with β-ZnSb and Zn phases, were prepared by solidification under high magnetic fields (HMFs). The microstructure evolution and thermoelectric (TE) properties of the alloys were then investigated. Zn phase precipitated as strip and presented reticulation structure in the samples without HMFs. When the HMFs were imposed, Zn became disperse and the strip of Zn became thinner and shorter. In addition, the c-axis of Zn crystals showed a tendency to orientate toward the direction perpendicular to the magnetic field direction. The samples prepared under HMFs had higher resistivity and Seebeck coefficient and lower thermal conductivity. When compared to the solidified samples without HMFs, the application of 8.8 T of HMF increased the maximum figure of merit 3.7 times. In addition, the relationship between microstructure and TE properties was also analyzed. [ABSTRACT FROM AUTHOR]

The effect of a magnetic force on creating an aligned two-phase microstructure in a Fe-0.25wt%C alloy under magnetic field gradients has been investigated. Through the changes in the heating temperature, both dipolar interactions and magnetic forces work together during the austenite to ferrite transformation. The results showed that the aligned two-phase microstructure is not observed under the influence of the magnetic force alone. The ferrite grains are elongated due to dipole interactions at the early stages of their nucleation and growth and then the magnetic force turns the elongated ferrite grains, whose major axis is not parallel to the direction of magnetic force, to the direction of the field in the presence of magnetic field gradients. [ABSTRACT FROM AUTHOR]

Structural evolutions of Co 561 clusters supported on the Cu(010) substrate were studied by molecular dynamics simulation using an embedded atom method. Energy, snapshot, pair distribution function and epitaxial factor were used to analyze the effects of supported position, configuration and temperature on the structural evolutions. It is found that the energy of the cluster changes significantly with varying the supported position and the original configuration. The most stable supported position is (111) facet. As a function of configuration the stability decreases in the order: icosahedron > truncated octahedron > decahedron > cuboctahedron > sphere. Supported (111) facet changes to stack along the (100) of substrate. Epitaxial growth on the substrate occurs for all configurations. The epitaxial temperature and the amount of epitaxial atoms are related to the configuration. The epitaxial growth is adverse to the stability of the cluster, while the epitaxy has no effect on the crystal structure of the supported cluster. The energy of the cluster is reduced by the epitaxial growth and atomic penetration into the substrate but is enhanced by the distortion of the cluster on the substrate. [ABSTRACT FROM AUTHOR]

In this study we have explored how a high magnetic field (HMF) affects the structure and magnetic properties of Fe thin films fabricated on Si (100) substrates at various substrate temperatures by using a thermal evaporation method. At a substrate temperature of room temperature (RT), the HMF increased the width of column and the formation energy of the films. This behavior occurred because the HMF induced an excess energy-Zeeman energy which is larger than the sum of the kinetic energy and thermal energy of Fe without the HMF. This increased the particle size and decreased the roughness of the film deposited at RT and 6 T. When the substrate temperature was increased to 400 °C, the growth mode is changed from columnar (RT) to layered (400 °C). The HMF increased the grain size. The film deposited at RT and 6 T had much improved soft magnetic properties from its modified microstructure. While thermal disturbances decreased the effect of HMF on the magnetic properties of the film deposited at 400 °C. In particular, the influence of HMF on the microstructure and magnetic properties of Fe films is significant not in the evaporation stage but in the condensation process of film. [ABSTRACT FROM AUTHOR]

Nanocrystalline Fe 30 Ni 70 (in atomic %) thin films were prepared by molecular-beam-vapor deposition in magnetic fields with different magnetic flux densities. The microstructure evolution of these thin films was studied by atomic force microscopy, transmission electron microscopy, and high resolution transmission electron microscopy; the soft magnetic properties were examined by vibrating sample magnetometer at room temperature. The results show that all our Fe 30 Ni 70 thin films feature an fcc single-phase structure. With increasing magnetic flux density, surface roughness, average particle size and grain size of the thin films decreased, and the short-range ordered clusters (embryos) of thin films increased. Additionally, the magnetic anisotropy in the in-plane and the coercive forces of the thin films gradually reduced with increasing magnetic flux density. [ABSTRACT FROM AUTHOR]

The Fe 60 Ni 40 (in atomic %) nanoparticles (NPs) thin films with 90 nm thickness were prepared on 25 and 400 °C quartz substrates by using the molecular beam vapor deposition (MBVD) method under a 6 T high magnetic field (HMF). The effects of a HMF on the structure evolution and properties of Fe–Ni thin films were studied by using X-ray diffraction, atomic force microscopy, transmission electron microscopy, vibrating sample magnetometer and four-point probe method. The results show that the crystallinity of thin films is enhanced by a 6 T HMF, and a 6 T HMF changes phase composition of thin films on 25 °C substrate. It is found that the nanoparticle size decreases; the nanoparticle size distribution becomes narrow, and the root mean square (rms) roughness of thin films decreases under a 6 T HMF relative to that without HMF. These lead to the decrease of coercive force, and the increase of in-plane remanence ratio under a 6 T HMF. [ABSTRACT FROM AUTHOR]

Abstract: We report on the influence of magnetic field strength on the alloy Tb0.27Dy0.73Fe1.95 during slow-cooling solidification. We examined the effect of magnetic field strength on microstructure, magnetization, and magnetostrictive properties of this giant magnetostrictive alloy. We found that after field-treated solidification, the microstructure of specimens had a distinct grain arrangement and displayed magnetic anisotropy. The crystal orientation changed from random in the field-free treatment to aligned along the 〈110〉 direction in flux densities of 1 and 2.2T, and along the easy magnetization axis 〈111〉 at a flux density of 4.4T. In consequence, the magnetostrictive coefficient of the samples under various stresses improved with increasing magnetic flux density. Both the d 33 and k 33 values and the energy transformation efficiency of the field-treated specimens showed strong enhancements. [Copyright &y& Elsevier]

Highlights: [•] We present the change of the crystal orientation and magnetostriction of TbFe2 based alloy during treatment in the semi-solid state in high magnetic fields. [•] Orientation of the TbFe2 phase undergoes a transformation of 〈113〉 to 〈111〉 to 〈110〉 with increasing magnetic flux density. [•] Magnetostrictive property is slightly lowered at 4.4T, but strongly enhanced at 8.8T and 11.5T. [ABSTRACT FROM AUTHOR]

Abstract: Isothermal heat treatment experiments of an Al–4.8mass%Cu alloy were carried out under different magnetic field intensities, at different temperatures and for different holding times. The influence of high magnetic fields on area fraction of θ phase in the solidified microstructure was investigated. It was found that the area fraction of the θ phase was lower when imposing the magnetic field compared to samples heat-treated without magnetic field. In other words, the magnetic field accelerated the phase transformation to the equilibrium state. In addition, the area fraction of the θ phase was independent of magnetic field intensity. This effect of high magnetic fields on the decreasing of the θ phase was discussed from the viewpoint of the effect of high magnetic fields on diffusion. [Copyright &y& Elsevier]

Abstract: Nanocrystalline Fe x Ni1−x (in at%, x=0.74, 0.6, 0.55, and 0.3) thin films were prepared on a 25°C quartz substrate by using a molecular beam vapor deposition method with and without a 6T magnetic field. The microstructure of the thin films was characterized by energy dispersive x-ray spectroscopy, x-ray diffractometry and transmission electron microscopy. The magnetic and electrical properties of the thin films were examined by a vibrating sample magnetometer and four-point probe method. Results show that the thicknesses of these films with different compositions are 50, 90, 80, and 150nm, correspondingly. The crystallinity of Fe x Ni1−x (x=0.74 and 0.6) thin films is enhanced, and the γ 〈111〉 orientation degree of the Fe x Ni1−x (x=0.55 and 0.3) thin films increases under a 6T magnetic field. The grain refinement and defect decrease under 6T magnetic field are affirmed by TEM. A 6T magnetic field can help the thin films transform from anisotropy to isotropy. The soft magnetic properties of the Fe x Ni1−x (x=0.74, 0.6, 0.55, and 0.3) thin films are enhanced, and their resistivities decrease under a 6T magnetic field. [Copyright &y& Elsevier]

Abstract: The magnetic properties of Fe–49%Sn monotectic alloys were investigated after the alloys were solidified with and without a high magnetic field of 10T. The results showed that there was a significant difference between their hysteresis loops measured parallel and perpendicular to the applied high magnetic fields for the solidification process. Therefore, high magnetic fields applied in solidification process increased the magnetic anisotropy in the alloys. Along the parallel directions of the high magnetic field applied in their solidification process, the saturation magnetization M s, magnetic susceptibility dM/dH M and remanent magnetization of Fe–49%Sn monotectic alloys were increased obviously, which resulted from the improvement in the aligned microstructure of Fe–Sn alloys by applying the high magnetic field to the solidification process. A modified Stoner–Wohlfarth model was introduced to explain the experimental results. [Copyright &y& Elsevier]

Abstract: Mn–89.7wt.%Sb alloy specimens were solidified in various magnetic fields with different holding times. The influence of the high magnetic field on the orientation of both the primary and eutectic MnSb crystals and on the alignment of the primary MnSb grains in the alloys has been investigated. It was found that the primary MnSb crystals were oriented with their c-plane parallel to the imposed magnetic field direction, but the eutectic MnSb from a eutectic MnSb alloy could not be oriented by the high magnetic field. The primary MnSb dendrites were aligned along the magnetic field direction. This alignment may be attributed to combined effects of crystal orientation, crystal growth feature and heat flow. [Copyright &y& Elsevier]

Abstract: The effects of high magnetic fields on the as-cast microstructure and grain boundaries of binary Al–Li alloy were investigated. It was found that secondary dendrite arm spacing (SDAS) decreased and the distribution of the SDAS became uniform under high magnetic fields. The application of a high magnetic field had no effect on the type of precipitated phases in the alloy, although δ′ (Al3Li) precipitates coarsened under the field of 11.5T. Area fraction of grain boundary (AFGB) slightly decreased at first and then increased with increasing magnetic flux density under uniform magnetic fields, while it decreased under magnetic field gradients. [Copyright &y& Elsevier]

Abstract: The formations of nanoclusters with different geometries are strongly related to the nucleation. This is of importance in controlling the structures of nanoclusters. In this letter, the freezing processes of (CoCu)309 clusters were studied by using molecular dynamics simulation with an embedded atom method. It is found that the frozen structures were significantly influenced by Co concentrations. An hcp structure was formed for Co229Cu80 and Co200Cu109 clusters and an icosahedral one was formed for the other clusters. Bond order parameter and pair distribution function were used to analyze the nucleation of the above structures. The results indicate that the icosahedron was formed almost at the same time on the surface and the inside of the clusters, while the hcp structure was formed from the inside to the surface. [Copyright &y& Elsevier]

Abstract: This paper studies the freezing of Co clusters with diameters ranging from 2.52 to 4.62nm by using molecular dynamics simulation with an embedded atom method. It was found that the frozen structures are closely related to cluster sizes. When the cluster size is small (≤2.94nm), an icosahedron is formed. When the cluster size is large (≥3.79nm), an hcp bulk-like structure is formed. If the cluster size is 3.37nm, a decahedron is formed. It was also found that the frozen structure is strongly dependent on the energy of geometric shapes at given sizes. The size-dependent frozen structures of clusters provide a new method for fabricating novel materials with nano microstructures. [Copyright &y& Elsevier]