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Four different configurations of single-atomic-layer-height disconnections on ( 10 1 ¯ 2 ) twin boundary in magnesium are investigated using molecular dynamics simulations. It is found that a prismatic-basal (PB) single-atomic-layer-height disconnection is more stable than a basal-prismatic (BP) single-atomic-layer-height disconnection when each of them is connected with an I1 stacking fault associated with a stacking sequence change of BA B CB. In contrast, a BP single-atomic-layer-height disconnection is more stable than a PB single-atomic-layer-height disconnection when each of them is connected with an I1 fault associated with a stacking sequence change of AB A CA. A stable BP (or PB) single-atomic-layer-height disconnection can transform to a stable PB (or BP) single-atomic-layer-height disconnection when its step orientation changes with a change in the lying plane of the connected I1 fault.

Self assembled monolayers (SAMs) of 1–tetradecylphosphonic acids (TDPA, CH 3 (CH 2 ) 13 P(O)(OH) 2 ) were formed on the 2024 aluminum alloy surface in TDPA-containing ethanol–water solutions with different water content. The adsorption and corrosion protection properties of the SAMs for 2024 alloy in 0.1 mol/L H 2 SO 4 solution were examined and characterized by potentiodynamic polarization, electrochemical impedance spectrum (EIS), Fourier transformed infrared spectroscopy (FTIR), Auger electron spectra (AES) and atomic force microscopy (AFM). FTIR and AES results show that the TDPA molecules were successfully adsorbed on the 2024 aluminum alloy surface, and the density of the SAMs increased with the increasing water content in the assembly solution. The results of electrochemical studies and corrosion morphologies observed by AFM show that a 4 h modification resulted in maximal inhibition efficiencyand the higher the water content in the assembly solution is, the better the inhibition performance of the SAMs can be achieved. The effect of water content in TDPA solutions on the performance of the SAMs is related to the hydration reaction of the metal surface.

The self-assembling behavior of 1-tetradecylphosphonic acid (TDPA) molecules on the surfaces of 2024 aluminum alloys was studied with an emphasis on the different micro-structural regions of the alloy surface, specially the alloy matrix and the two main types of intermetallic particles, as well as how the adsorption was effected by changes in water content of the self-assembly solution. Surface characterization was undertaken with contact angle measurement, scanning electron microscopy and Auger electron spectroscopy (AES). The packing density of TDPA film on the alloy surface increased with the increasing water content of the self-assembly solution. It seemed that the micro-distribution of TDPA molecules was related to copper amount and the region with a higher surface copper concentration had a lower packing density of TDPA. Some pits were formed in the acidic self-assembly solutions and the exposed surfaces of the pits can quickly adsorb TDPA molecules with compactness comparative to the matrix surface. Different adsorption models of TDPA corresponding to different water content of the self-assembly solution were suggested based on the analysis of AES depth sputtering data. Copyright © 2013 John Wiley & Sons, Ltd.

The Ni-P-Al2O3 composite film was coated on mild steel of SS400 with electroless plating method. In this process, different sizes of Al2O3 particles and different blended amounts of Al2O3 particles into the plating solution were applied. From the surface and cross section observation, it is known that the Al2O3 particles were uniformly dispersed in the Ni-P alloy. The highest corrosion resistance and the highest wear resistance of the Ni-P-Al2O3 composite film were obtained when adding Al2O3 particles with the mean diameter of 0.05μm into the plating solution at the blended amount of 1.0g/L.

A Mg–6Gd–1Zn–0.6Zr alloy has been mechanically tested in the aged and solution treated conditions. The plate showed negligible yield asymmetry in either the aged condition or the particle free condition. This has been attributed to the weak texture that develops during recrystallisation. It is proposed that a negligible yield asymmetry can be achieved with textures weaker than ∼ 5 times random intensity, and that it is not necessary to have a fully random texture, but simply a texture weak enough for basal slip to dominate the deformation in both tension and compression. The ageing treatment provided little strengthening in tension or compression, and this is because the precipitates do not possess the strongest hardening characteristic of coherent shearable particles, which is internal order.

Die-cast Mg–La, Mg–Ce and Mg–Nd binary alloys varying in composition have been used to investigate creep resistance and its relation to microstructure. The remarkable differences in creep resistance observed in these alloys are shown to be related to different levels of rare earth (RE) solute supersaturated in the α-Mg matrix. The results seem to suggest that strengthening of the α-Mg matrix by solid solution and/or precipitation is more important than grain boundary reinforcement by intermetallic phases for the creep resistance of Mg–RE alloys.

The addition of Ag to Mg–Y–Zn alloys provides these alloys with the ability to develop a strong age-hardening response. In this work, the as-cast microstructure of an age-hardenable Mg–6Y–2Ag–1Zn–0.6Zr (wt%) alloy processed by conventional ingot metallurgy has been investigated by a transmission electron microscopy. Three distinct intermetallic phases are detected in the as-cast microstructure, two of which are similar to those phases present in the as-cast Ag-free Mg–Y–Zn alloys. The third is a previously unreported intermetallic phase associated with the additional element of Ag. The crystal structure of this phase is determined as diamond-cubic structure (a = 1.59 ± 0.01 nm, ). The dispersed particles of this phase often have a substructure of twinning on { 111} planes.

The planar features in a Mg–8Y–2Zn–0.6Zr (wt.%) alloy solution-treated at 500 °C for 1 h have been examined using conventional transmission electron microscopy and atomic-resolution high-angle annular dark-field scanning transmission electron microscopy. Three types of planar features are detected in the microstructure. The first type, which was previously reported to be an intrinsic stacking fault I1 bounded by a Frank partial dislocation, is shown to be the 14H precipitate phase that is associated with Shockley partial dislocations. The second type is also a precipitate phase that has a single unit cell height and is associated with Shockley partial dislocations. The third type of planar feature comprises small ribbon-like stacking faults. These stacking faults are determined as intrinsic I2 type bounded by two Shockley partial dislocations, which is further confirmed by computer simulation. The stacking fault energy associated with the faults is much smaller than that of pure magnesium.