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This study is devoted to establish the relationship between high angle grain boundaries (HAGBs) and hardness from crystallography and provide reference for improving the hardenability of high stren...

We investigated the evolution process of equilibrium lattice parameter (ELP), magnetic properties and electronic structure from nonmagnetic semiconductive CoFeTiAl to ferrimagnetic CoFeFeAl in theory and experiment. The theoretical results show that CoFe 1+x Ti 1−x Al compounds have a diluted magnetism with a 100% spin-polarized ratio at the Fermi level when X is less than 30%. When X is in the range of 30%–60%, CoFe 1+x Ti 1−x Al compounds have also a high spin-polarized ratio. The ELP and magnetization have a gradual and linear change with the increasing Fe level in the ranges of X = 0–50% and 70%–100%. An unexpected sharp jump in ELP and magnetization occurs near the composition point of X = 65%, which was attributed to band Jahn-Teller effect. In experiment, CoFe 1+x Ti 1−x Al (X = 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) compounds with Heusler structure were successfully synthesized. The experimental results are in agreement with the theoretical results when X is less than 30% or higher than 70%. The sharp jump in ELP and magnetization are experimentally observed near the composition point of 65%. The deviation of the experimental magnetization from theoretical results in the range of 50%–70% is attributed to the theoretical underestimation to ELP. We predict that by the same mechanism of the band Jahn-Teller effect, the sharp change in the magnetization and lattice parameter should also be possible to occur with the changing temperature for a certain composition of CoFe 1+X Ti 1−X Al compounds. A new type of ferromagnetic shape memory alloys based on a martensitic transformation with an invariant crystallographic symmetry is proposed.

Effects of heat treatment on microstrucutures of a Re-containing single crystal superalloy have been investigated. The results showed that (γ+γ′) eutectic in as-cast alloy is practically dissolved with solution heat treatment, and the degree of segregation is distinctly decreased. The size, morphology and distribution of γ′ phase are mightily affected by the first-stage ageing treatment temperature. When the first-stage ageing treatment temperature lower than 1160°C, the shape of the γ′ phase is cubic. But the γ′ phase shape is transformed to sphericity when the temperature higher than 1180°C. The γ phase channel width is significantly increased, and the fine γ′ phase precipitated in the γ phase matrix channel.

Nanocomposites of Poly(butylene succinate) (PBS) and poly(∊-caprolactone) (PCL)-coated nano-TiO2 (C–TiO2) are prepared by melt-blending technique. The influence of high loading C–TiO2 on the microstructure, mechanical, thermal and dynamic rheological properties of pure PBS and its nanocomposites are studied. Scanning Electron Microscope results demonstrate that the surface modification and content of TiO2 are main factors to affect the microstructure of composites. Mechanical tests show that adding C–TiO2 into PBS matrix is an effective way to improve the impact strength of the PBS. Impact property and tensile property are sensitive to different microstructure, the former is distance between particles and the latter is the aggregation of particles. Dynamic rheological tests show that the incorporation of C–TiO2 particles into PBS can improve the elastic properties of PBS nanocomposites and restrict the mobility of PBS chains. Differential scanning calorimeter indicates the addition of C–TiO2 can increase the crystallization rate but do not influence the main PBS crystals. Depending on the state of composites, the C–TiO2 restricts or improves the mobility of PBS molecules.

The TEM chamber is a proposed exposure device for experiments detecting cell responses to electromagnetic irradiation at the mobile frequency of 900 MHz. In this paper, we extend the traditional propagating-wave exposure to the standing-wave exposure. Four standing waves with different properties are produced respectively by two types of passive loads and two types of active loads. Systematically, the maximum E field and maximum H field of the standing waves are used to expose Petri dishes of three sizes. The standard deviation (SD) of the specific absorption rate (SAR) is calculated for the cell layer and the cell suspension. We compare the SD data to determine the best arrangement with the highest exposure uniformity while considering the exposure intensity. The investigation uses the numerical simulation of the finite-difference time-domain (FDTD) method with the result accuracy supported by comparison to theoretical data on the field distribution in the TEM chamber.

The operation of an all solid-state pulsed Nd:KGW Raman laser pumped by compact passively Q-switched Nd:YAG/Cr:YAG laser is demonstrated. The first-Stokes radiation of stimulated Nd:KGW Raman scattering at the 1178 nm is generated. The average output power of 336 mW at Stokes wavelength was obtained under the laser diode pump power of 5.74 W. The corresponding optical efficiency from the diode light to the Raman output is 9.85%. The pulse width of 1.65 ns and a pulse repetition rate of 10 kHz were also obtained.

A numerical dosimetry is performed for experiments studying effects on cornea cells cultured in Petri dishes exposed to 50 GHz millimeter wave (MMW). An algorithm is developed to calculate the incident field from a six-degree-freedom MMW radiator, with respect to its specified position and orientation. With the algorithm, the finite-difference time-domain (FDTD) method simulated the interaction between the incident MMW and the Petri dishes. The specific absorption rate (SAR) in cells and the homogeneity of the SAR distribution are calculated and analyzed for dosimetric assessment in related MMW experiments on cells in vitro.

One sort of experiment concerning biological effects of millimeter waves (MMWs) at the cellular level is performed using a culture dish containing a cell monolayer with MMW irradiated from the underneath. For culture dishes with diameters much larger than the wavelength, analysis is carried out with respect to the relationship between the portion of the incident MMW power density (PD) received by the cell monolayer and influencing factors such as the culture dish bottom thickness, MMW wavelength, and the electromagnetic properties of the dish and culture solution. Another analysis is conducted by the FDTD method to reveal the effect of culture dish configuration on MMW PD received by the cell monolayer in a typical culture dish with a diameter not much longer than the wavelength. With the illustrated results, the conclusion is reached that rigorous analysis, precise measurement and accurate calculation of MMW PD should accompany such experiments, and large-diameter culture dishes are more preferred in experiments to small-caliber dishes.

A general numerical method is presented for calculating steady three-dimensional and two-phase turbulent reactive flows with a nonstaggered body-fitted coordinate system in an annular gas turbine combustor with the dump diffuser. The modified two-equation model and the EDC turbulent combustion model are used for the gas phase. The liquid phase equations are solved in a Lagrangian frame of reference by PSIC algorithm. The effect of different velocity profiles at the entry of the prediffuser on combustor flow characteristics is calculated.

This paper presents an overview of mechanical properties and constitutive law for wood. Current research on the mechanical properties of wood have mostly focused on density, grain, moisture, and other natural factors. It has been established that high density, dense grain, and high moisture lead to higher strength. In most literature, wood has been regarded as an anisotropic material because of its fiber. A microscopic view is used in research of wood today, in this way, which has allowed for clear observation of anisotropy. In general, wood has higher strength under a dynamic load, and no densification. The constitutive model is the basis of numerical analysis. An anisotropic model of porous and composite materials has been used for wood, but results were poor, and new constitutions have been introduced. According to the literature, there is no single theory that is widely accepted for the dynamic load. Research has shown that grain and moisture are key factors in wood strength, but there has not been enough study on dynamic loads so far. Hill law has been the most common method of simulation. Models that consider high strain rate are attracting more and more attention.