Advanced Materials Research Vol. 937

Abstract: Equal Channel Angular Pressing (ECAP) and Surface Mechanical Attrition (SMAT) are the two Severe Plastic Deformation (SPD) processes that have been used to process ultrafine grained (UFG) materials. These two kinds of processes have been used to refine the grain size of coarse-grained commercial pure titanium (CP-Ti). The development of microstructure during equal channel angular pressing (ECAP) and surface mechanical attrition (SMAT) of commercial pure titanium (CP-Ti) is investigated to establish the mechanisms of grain refinement. Based on the various experimental results and analysis, it has been found that the high-strain-rate and many direction loading is conducive to the formation of nanograins and also the grains with less than 100 nm cannot be obtained by the single equal channel angular pressing (ECAP).

Abstract: Corrosion experiments were applied for 13Cr steel. Through the experiments, the corrosion rate of 13Cr steel in different temperature was tested. The corrosion rate of 13Cr steel was increased with the increase of temperature. Moreover X-ray diffraction analysis and scanning electron microscope analysis were applied to understand the corrosion behavior of 13Cr in micro-scale.

Abstract: In this paper, AZ31B magnesium alloy/LY12 aluminum alloy were bonded together with copper foil as interlayer by vaeuum diffusion bonding technology at different temperature for holding time 60 min and pressure 2.5MPa. Analysis the microstructure of the joint under the condition of 450°C,and the effects of heating temperature on the shear thrength , microhardness and the width of the interface zone were studied. The results showed that under the condition of 450°C in holding time 60 min and pressure 2.5MPa, the microstructure at interface zone of diffusion brazing joint includes α-Mg solid solution, Mg₂Cu, Cu₂Mg, γ-Cu solid solution, CuAl, CuAl₂ and β-Al solid solution. The width of the interface increases with brazing temperature increasing, and the microhardness gradient of interface zone in the side of aluminum alloy is much higher than that in magnesium alloy side. As the welding temperature increases, the shear strength shows an increasing trend at first and then decreases. When the welding process is 460°C keeping for 60 min, welding pressure is 2.5Mpa, the highest shearing strength of the joint can reach 35 MPa.

Abstract: Magnesium alloys as the emerging commercial metal structure material have excellent specific properties, low density, and stability, which are more and more vital for researchers. This paper reviews the behavior of rare earth in magnesium alloy and the way to enhance the elevated temperature properties of Mg-RE alloys. The current Mg-RE alloys are summarized. The future development direction is pointed.

Abstract: The influence of the solution treatment (at the temperature of 500-520°C for 4-12 h) on microstructures and mechanical properties of Mg-Gd-Y-Zr alloy was investigated by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Vickers hardness measurement. The as-cast alloy contains a microstructure consisting of α-Mg matrix, Mg₅Gd phase and Mg₂₄Y₅ phase. With increasing solution temperature and time, the quantity of the primary particles (Mg₅Gd and Mg₂₄Y₅) in the alloy continually decreased, and the degree of recrystallization gradually increased, which result in the gradual decrease of the Vickers hardness of the solution-treated alloys.

Abstract: A large amount of dust can be produced in iron and steel making process. This paper analysis the chemical composition, particle size distribution and microscopic characteristics of those iron and steel making dust. Some dust with high iron content, some dust with much CaO and some dust with carbon, those indicate that the iron and steel making dust can be used as iron making raw material. But the size of the iron and steel making dust is very small, which will make it harder to deal with those dust.

Abstract: This paper deals with manganese electrodeposition from an chloride electrolyte without and with acetate and the resultant deposit properties. The addition of acetate to the plating bath reduces the rate of manganese deposition abserved under cyclic voltammetry and in situ Spectroscopic ellipsometry. The addition of acetate improves the corrosion resistance of the manganese deposits. The XRD pattern obtained for electrodeposited manganese show a pure α-Mn with polycrystalline nature no matter with or without acetate. A uniform and pore free surface was observed under SEM analysis in the two plating baths.

Abstract: Various natural contamination components distributed on the surface of high-voltage insulators play important roles on the flashover hazard. Under the low humidity condition, the flashover voltage could be affected considerably by the sucrose contaminations. Molecular dynamics simulations have been carried out in order to reveal the microscopic mechanisms for the sucrose-involved flashover uptake. It is found that the diffusion of ions decreases significantly and thus the conductivity of aqueous medium is lowered apparently. In the presence of sucrose, the contact ion pairs formed between Na⁺ and Cl^- ions are enhanced because both ions are less coordinated to water molecules. The influence of the external electric fields on the diffusion and conductivity were investigated as well. It is suggested that the sucrose contamination might lead to the uneven electric fields on the insulator surface.

Abstract: A novel doping scheme for graphene was recently realized experimentally by creating different vacancy complexes doped with a transition metal (TM) atom [nanoLett. 12, 141 (2012)]. This provides a new reliable way to modifying the electronic structure and transport property of graphene. Here, we show, by performing first-principles calculations, that the defect complex of TM@V₄ (a TM atom doped tetra-vacancy) in zigzag graphene nanoribbons (ZGNRs) can lead to a 100% spin-polarized electron transport in a wide energy range around the Fermi energy. Analyses show that this is due to the particular atomic structure of the TM@V₄ complex regardless of the species of the TM atom.

Abstract: The effect of N, N-diethylthiourea (DET) upon the microvia filling by Cu electrodeposition was investigated by cross-sectional images using optical microscopy. The bottom-up filling of the electroplating bath was achieved with an addition of DET. The electrochemical study indicated that the polarisation on the cathode was increased with an addition of DET. The results present DET as an accelerator which is beneficial for microvias filling for high density interconnections printed circuit board.