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The influence of anodized film on corrosion and electrochemical behavior of extruded magnesium alloy AZ63, cast and die-cast magnesium alloys AZ91D were investigated by using immersion technique, electrochemical methods, SEM, EDAX, IR and XRD. The results showed anodized film could improve remarkably corrosion resistance. Protection effect was different with the same anodizing process because formation status of anodized film of different materials was different. The formation status of anodized film was related to alloy microstructure as revealed by optical and scanning electron microscopy. The formatting process and casting method strongly influences the corrosion performance by affecting on the alloy microstructure. A tentative corrosion mechanism is presented explaining the corrosion behavior of anodized magnesium alloy.

Microstructure and tensile properties of squeeze cast Mg-Al-Ca alloys with different levels of calcium addition (AMC50X) were studied. The microstructural analysis by optical and scanning electron microscopy (SEM) shows that the squzeeze cast Mg-Al-Ca alloys contain primary α-Mg, (Al, Mg)₂Ca and Mn-Al intermetallic while the base alloy AM50 contains primary α-Mg, β-Mg₁₂Al₁₇ and Mn-Al intermetallic. The addition of calcium varying from 1 to 4 wt.% increases the fraction area of Ca-containing secondary phases from 9.5% to 19.5%. The experimental observation confirms also that the calcium has a grain refining effect on the base alloy AM50A. The tensile testing results indicate that, as the calcium content of AMC50X alloys increases from 0 to 4%, the ultimate tensile strength (UTS) and elongation (E_f) decrease dramatically at room temperature as their yield strengths (YS) improves slightly. At 150°C, however, both the UTS and YS of the alloys increase with increasing the Ca content.

In this study, constitutional liquation in AZ91 cast alloy at 440°C and 465°C was experimentally simulated. Metallurgical examination was conducted to reveal the morphology of the constitutional liquid and dihedral angle was measured to evaluate the wettability of the liquid on grain boundary. Dihedral angle was found to be initially ~30 degree and thus grain boundaries were incomplete wet. During annealing, the metastable constitutional liquid resolidified, followed by grain growth. The extent of grain boundary wetting by the remaining liquid increased slightly with treating time. The rate of resolidification was also evaluated and the factors affecting this rate were discussed.

Porous Mg alloys will be promising orthopedic implants materials. In this study, porous Mg–Zn alloy with a porosity of 30% was prepared by powder metallurgy process. XRD was used to examine the composition of the sample and synchrotron radiation-based X-ray micro-computed tomography (SR-μCT) was used to investigate the pore properties of the sample. The results showed that the sample comprised a single Mg phase and a Mg₂Zn₁₁ phase. The SR-μCT results showed that the porosity of the sample is about 30% which is approximate to the theoretical porosity. The pore morphology was irregular and the largest pore was about 200 μm in diameter. And a large pore cluster was identified meaning that most of the pores in the sample were interconnected with each other. This is beneficial for the materials transformation after the implantation of the sample in human body, which will boost the bone regeneration. Drug-loading experiment showed that Ibuprofen can be successfully loaded in porous Mg–Zn alloy, which means that porous Mg–Zn alloy could be an orthopedic drug delivery system (DDS).

In this paper is presented and discussed the damage tolerance and fracture characteristics of three rapidly solidification processed magnesium alloys. Test specimens of the magnesium alloy were deformed under both quasi-static and fully reversed total strain amplitude controlled cyclic loading. The quasi-static and cyclic stress response characteristics are discussed in light of the competing and synergistic influences of nature of loading, response stress, intrinsic microstructural effects, dislocation-microstructural feature interactions and macroscopic fracture.

The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated. The studies were carried out in 3.5% NaCl solution at pH 7.25 using constant immersion technique, potentiodynamic polarisation experiments and surface topographic analysis. Microstructural areas with aluminium concentration less than about 8% (primary α phase and surroundings) were found to be more prone to corrosion attack compared with either those with higher amount of aluminium (eutectic α phase and its surroundings) or β phase. Die-cast material with smaller grain size and fine β phase offered marginally higher corrosion resistance and better passivation compared with the ingot.

The influence of chloride ion concentration and pH on the corrosion and electrochemical behaviour of die-cast and ingot cast AZ91D alloy has been investigated. The experimental techniques used include constant immersion test, potentiodynamic polarisation and scanning electron microscopy. Die-cast and ingot showed a linear increase in corrosion rate and I_corr with increase in chloride ion concentration with a change in slope for ingot above 5% NaCl. Open circuit corrosion potential shifted to more negative (more active) values as chloride ion concentration increases. The corrosion rate and I_corr are very high in highly acidic conditions (1-2.0 pH) and tend to decrease as pH increases. A synergism has been observed between the effect of chloride ion concentration, pH and microstructure of the material. Observation of the corrosion morphologies revealed preferential attack on β (Mg₁₇Al₁₂) and adjacent α regions (α regions with higher Al content) in highly acidic and higher chloride ion concentrations.

The solidification microstructure of AM60 magnesium die casting has been studied using optical and transmission electron microscope (TEM). The results showed that the microstructure of magnesium die casting displayed a divorced eutectic [Mg(α) + Mg₁₇Al₁₂(β)] structure. There was a thin layer adjacent to the surface with a considerably finer microstructure than the interior of the magnesium die castings, which caused the hardness of the skin layer was about 15~20Hv higher than the interior area. Porosity measurement showed that the highest porosity content was at about 60~80mm away from the gate and at the central area of test bar which sites are of the strongest turbulence.