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The microstructure and mechanical properties of Al-Zn-Mg alloys with low Zn/Mg ratios have been studied.According to various researchers, the major strengthening is due to η-phase and T phase. There are many briefly research on the microstructure and interface of the η-phase types but not briefly information about the T-phase That’s why now our aim to work on T-phase. In actual our aim is to observe the T-phase interface. The MgZn2 phase (η phase) and its metastable phase (η′ phase) were the most prominent precipitates. Another study revealed various Mg32(Al, Zn)49 phases (T phase) and their metastable phase (T′ phase) in Al-Zn-Mg alloys with low Zn and high Mg content. Al-Zn-Mg alloys with a Zn/Mg ratio of 0.71 were explored for this study. The alloy with a Zn/Mg ratio of 0.71 aged at 473k for 2000 minutes exhibited the highest hardness, according to the observations. The strengthening precipitates in the investigated alloy were totally T′ phase, according to TEM observation.

In this study, we investigated the influence of the interaction between graphene and other materials as a basis for controlling the electronic structure of nanocarbon materials. First-principles calculations based on density functional theory (DFT) were performed on the optimized structure, adsorption energies and electronic states when copper and aluminum atoms were placed on graphene. As a result, we found that copper and aluminum are stable at the bridge and the hollow site, respectively. It was found that the adsorption energy of aluminum atom on graphene is larger than that of copper atom. It is considered that the difference in adsorption energy is caused by the difference in the dominant electron orbitals of the copper atom and the aluminum atom.

A density functional theory (DFT) is used to investigate the energetics of an epoxy resin adhere on a tin oxide and a hydroxylated-alumina surface within a supercell approach. Self—consistent geometry optimization is performed for models of adhesion interface, which is comprised of a fragment of epoxy resin and hydroxylated-Al2O3 (001), and SnO2(001) and (110) surface. The epoxy resin studied was simplified fragment based on diglycidyl ether of bisphenol A (DGEBA). It is found that the distance between the resin and the surface where the adhesion force is maximized is substantially the same for all models. Analysis of the energy-distance plot reveals that the fragment of DGEBA molecule adhere most strongly to the SnO2(001) surface, suggesting that the adhesion force is induced by van der Waals (vdW) interaction.

Metastable phases in aluminium alloys are the primary nano-scale precipitates which have the biggest contribution to the increase in the tangible mechanical properties. The continuous increase in hardness in the 7xxx aluminium alloys is associated with the phase transformation from clusters or GP-zones to the metastable η′ phase. The high-resolution electron imaging is used to observe the precipitates and reconstruct a kinetic model that might explain the transformation. This work is an attempt to gain insight into how the structural transformation may occur based on the shortest route of diffusion for the eventual structure to result in that of the η′ phase.

Metastable phases in aluminium alloys are the primary nano-scale precipitates which have the biggest contribution to the increase in the tangible mechanical properties. The continuous increase in hardness in the 7xxx aluminium alloys is associated with the phase transformation from clusters or GP-zones to the metastable ?' phase. The high-resolution electron imaging is used to observe the precipitates and reconstruct a kinetic model that might explain the transformation. This work is an attempt to gain insight into how the structural transformation may occur based on the shortest route of diffusion for the eventual structure to result in that of the ?' phase.

The geometric structure and electronic properties of the adsorption of organic carboxylic acids on the closed-packed Cu(111) surface have been addressed by periodic density functional theory (DFT) calculations. We also have taken into account van der Waals (vdW) interaction by the VdW-DF method. The optimized structures show that formic and acetic acids have stable structures of molecular adsorption in clean copper surfaces. We find that the adsorption energies at 1/16 ML coverage are -0.27, -0.30 and -0.10 eV for formic, acetic, and propionic acid, respectively. On the other hand, in the case of vdW-DF, their adsorption energies increased to -0.63, -0.70 and -0.73 eV.

Using density functional theory (DFT) we investigated the adsorption of chlorine atom on aluminum surface in the orientations, (100), (110), and (111). The structural and thermodynamic properties of chlorine atoms adsorbed on the Al (100), Al (110), and Al (111) surface for chlorine coverages of 1/9, 1/4, 1/3, 1/2, 3/4, and 1 monolayer (ML) are calculated. The largest bond strength is observed for a top, fcc, and hcp mixed structure at 3/4 ML coverage on Al (111). Adsorption free energy analysis reveals that the chlorine coverage of 3/4 ML of Al (111) is the most thermodynamically stable over the widest range of chlorine chemical potential and 1 ML of Al (111) is thermodynamically unstable, whereas various chlorine coverages of Al (100) and Al (110) take stable phase for a range of chlorine chemical potential.

The copper alloys, which were added Nickel show high corrosion resistance. Therefore, they are generally used in environments of poor quality fuel. However, it is expected that we reduce the amount of Ni in copper alloy, due to increase of Nickel consumption in recent years. We used five different types of sintered material samples that are different in the content of Nickel in the present study, to investigate the influence of Ni content to corrosion resistance quantitatively. These samples were used for the experiment of open circuit potentials, anodic and cathodic polarization curves measurements. To simulate environment in poor quality fuel we employed solution of 0.5 M Na2S + 0.1 M NaOH (pH = 13.05). The experiment of open circuit potentials shows that samples that the content of Nickel is less than 42 mass% were formed passivation film on surface of sample during aeration. The experiment of polarization curves measurements show that the each sample was implied behavior of forming passivation film corresponding to potential-pH diagram of Cu in anodic region basically. In addition, the 36.4 mass% Nickel was remarkably improved corrosion resistance.

Computational density functional theory (DFT) model of the adsorption of chlorine atoms onto the perfect Al (111) surface has been performed. The structural and electronic properties of chlorine atoms adsorbed on the surface are investigated within a supercell approach for chlorine coverages of 0.25, 0.33, 0.5 and 1 ML respectively. It is found that the adsorbates prefer on-top sites over bridge, hcp and fcc sites in low coverage while fcc sites in high coverage, and the binding energy decrease with increase of coverage due to the interactions of chlorine atoms. The discussion of geometrical and electronic analysis by plotting differential charge density distribution and projected density of states (PDOS) are presented.

Spin polarized density functional theory calculations have been performed to characterize the structure of water molecules on iron surface under applied charges. It is found that water molecules of the contact layer take H-down configuration under the negative charge, on the other hand, under the positive charge, they adsorbed on a top site of iron atom, as the applied charge increases, the dissociation of water molecules proceed. In addition, we found that the energy shift of the Fermi level varies linearly in the range from-e to +e, while beyond this range it tends to saturate.

We present the results from first principle calculations of H2O adsorption on oxygen-covered Fe (100) surface. The calculations are based on a density-functional theory, surface modeling which uses supercell slab models. As a surface oxygen coverage increases, the surface is not activated, which makes the adsorption of water molecules on Fe surface unfavorable. It has been found that the surface covered oxygen exerts an influence on the adsorption of H2O molecule on Fe surface.

In this experiment two kinds of 410L stainless steel, i.e., the first one is prepared by the I/M process and the second one is prepared by MIM process were used, and their corrosion behavior under stress in deionized water and the aqueous solution of 0.01kmol·m-3HCl+1.72mol·m-3MgCl2 (pH=2.33) has been investigated by Electrochemical Impedance Spectroscopy (hereafter shortened as EIS) under Slow Strain Rate Tensile (hereafter shortened as SSRT) test. The charge transfer resistance (Rct) of the I/M specimen is larger than that of the MIM specimen irrespective of under stress or non-stress, which means that the I/M specimen has the better corrosion resistance than the MIM specimen in the 0.01kmol·m-3HCl+1.72mol·m-3MgCl2 (pH=2.33) solution. It was also confirmed from the fracture surface observation that hydrogen embrittlement occurred on the MIM specimen in the aqueous solution of 0.01kmol·m-3HCl+1.72mol·m-3MgCl2 (pH=2.33). This result would be confirmed to be due to the existing impurities and defects in the MIM specimen.

In this study, the electrochemical measurements such as the potentiodynamic polarization and the electrochemical impedance spectroscopy (EIS) tests were carried out in order to clarify the corrosion behavior of the aluminum alloys fabricated by powder extruded (P/E) process compared with those by ingot metallurgy (I/M) process, using 6000 system aluminum alloys. Two kinds of aluminum specimens; one is fabricated by the conventional I/M specimen and the other is fabricated by the P/E process, were used for the electrochemical experiment in the sulfuric acid solution with 0.5 kmol/m3 concentration. Both of I/M and P/E specimens showed the linear relationship between the electrochemical potential (E) and the common logarithm of current density (icorr) in the cathodic region where Tafel law was recognized irrespective of stirring of the test solution though the icorr was slightly increased by stirring for both specimens. On the other hand, in the anodic region, both of the two specimens indicated the almost the same icorr irrespective of stirring. These experimental results interpret that the corrosion is controlled by the chemical reaction. The EIS test indicated that the maximum charge transfer resistance (Rct) was observed at -0.55 V which is 0.11 V higher potential than the corrosion potential (Ecorr) for both of the two specimens.

The behavior of water molecules with sulfate on the Fe(001) surface has been investigated using a first-principles method based on density-functional theory (DFT) with numerical atomic orbitals as basis functions for the description of valence electrons and nonlocal pseudopotentials for the atomic core. We present results for the adsorption structure and the bonding nature as caused by the adsorption-induced variations in the electron density and the projected density of states. We have found that the structure of absorbed sulfate depends on the coverage of water molecule on the surface. Analysis of electrostatic potential at an aqueous metal interface provides an appropriate framework to understand complicated potential structures. The mechanism of proton transfer through dissociative adsorption and hydrogen bonding of water molecules has been obtained from calculated results.

Two kinds of pure titanium specimens, i.e., the first one is prepared by the ingot metallurgy (I/M) process and the second one is prepared by the metal injection molding (MIM) process were used in this experiment, and their corrosion behavior under stress has been investigated in several aqueous solutions by Slow Strain Rate Tensile (SSRT) test. Ti MIM specimen showed the larger maximum stress and the lower maximum stain than I/M Ti specimen in the deionized water. Both Ti I/M and MIM specimens indicated good corrosion resistance in the aqueous solution of 2.5 kmol/m3 H2SO4 + 0.2 kmol/m3 NaCl in which SUS304 stainless steel showed SCC, and showed the decrease of the maximum stress and the maximum strain in the aqueous solutions of CH3OH + 0.1 kmol/m3 HCl, where the brittle fracture appearance was more remarkable with an decrease of H2O in the solution.