W.M. Wang

Casting Atmosphere Effects on the Precipitates, Magnetism, and Corrosion Resistance of Fe78Si9B13 Glassy Alloys

The precipitates, magnetism, and corrosion resistance of Fe78Si9B13 glassy samples fabricated in vacuum and air atmospheres (labeled as VAC and AIR samples, respectively) were studied. The findings show that the fraction of the amorphous phase in VAC samples is lower than that in the AIR counterparts. The Fe phase in VAC samples grows preferentially along the 〈200〉 orientation. The distribution of magnetization M4000 of VAC samples oriented parallel and orthogonal to the field (H// and H⊥) at H = 4000 Oe is more scattered than AIR samples. The corrosion resistance of VAC samples is lower than AIR counterparts, which can be attributed to the minor alloying effect of oxygen and the passive effect of silicon atoms supplied from the amorphous phase.

On the magnetic anisotropy in Fe78Si9B13 ingots and amorphous ribbons: Orientation aligning of Fe-based phases/clusters

Magnetic anisotropy in Fe-based amorphous ribbon plays an important role in various applications and is still not fully understood. To gain an in-depth understanding of this phenomenon, the structure and magnetic properties of Fe78Si9B13 master alloy ingots and melt-spun amorphous ribbons were measured by various techniques. For the ingot samples, both the α-Fe and Fe2B axes are aligned parallel with the radial direction (RD) of the original cylindrical ingot, i.e. the maximum temperature gradient direction, and their other orthogonal axes have several preferred directions in the plane vertical to RD. The hard magnetic axis of the ingot samples is parallel to RD, which is due to the large magnetocrystalline anisotropy energy difference between and {001} of the Fe2B phase. For the amorphous ribbons, there is an in-plane magnetic anisotropy: the easy or hard axis of magnetization is aligned on the plane of the ribbon, and parallel to or at an angle of about 60° to its width direction, respec...

Preparation and characterization of single crystalline anatase TiO2 films on LSAT (001) by MOCVD

TiO2 thin films with anatase structure have been prepared on [LaAlO3]0.3[SrAl0.5Ta0.5O3]0.7 (LSAT) (001) substrates by metalorganic chemical vapor deposition (MOCVD) in the substrate temperature range of 500–650 °C. Tetrakis-dimethylamino titanium (TDMAT) is used as the organometallic source and oxygen as oxidant. Structural and optical properties of the films as well as the epitaxial mechanism have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and optical transmittance spectra. The measurements and analyses show that the TiO2 film grown at 550 °C exhibits the best crystallinity with anatase structure. The obtained TiO2 film is a single-crystalline epitaxial film with no twins and very few defects. The heteroepitaxial relationship is determined as TiO2 (001) ‖ LSAT (001) with TiO2 [100] ‖ LSAT 〈100〉. The average transmittance of the film deposited at 550 °C in the visible wavelength is about 84% with an optical band gap of about 3.27 eV.

Structure characterization of amorphous Al83Ni10Ce5Si2 under the relaxed annealing

In order to trace the structure evolution of amorphous Al83Ni10Ce5Si2 before crystallization, the alloy viscosity (η) was measured by methods after annealing treatment at various temperatures. It is found that the alloy viscosity decreases initially and then increases with the annealing temperature. The X-ray diffraction (XRD) patterns show that the variation of the height of the main peak with annealing temperature (Hmax − T) is similar to that of the viscosity versus anncaling temperature (η − T), implying that the short-range order (SRO) in the amorphous alloy has changed. Additionally, the locations of the main peak and prepeak in the XRD curves move toward the high angle, implying that the characteristic spacing in the amorphous alloy decreases and that its volume decreases with the increase of the annealing temperature. The volume decrease is also confirmed by the development of the grooves on the free surface of the amorphous ribbon.