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A newly developed magnesium alloy Mg–5Gd–4Y–0.5Zn–0.5Zr (GWZ540) was hot extruded and then compressed at temperatures between 573 and 673 K and strain rates ranging from 2 × 10 −4 to 2 × 10 −1 s −1 . The stress–strain behaviors and volume fraction of dynamic recrystallized (DRX) grains were determined. It is shown that the form of the flow stress curves is sensitive to temperature and strain rate and DRX mechanisms of the alloy varied as deformation progresses. High density dislocation was formed at boundaries of coarse grains and around some particles of second phase at first. Dislocation cell walls then were formed and converted into subgrain boundaries. New recrystallized grains were formed finally at the base of subgrain boundaries and particles of second phase.

Phase equilibrium of the Mg–Gd–Y system in Mg-rich corner was calculated in detail by phase diagram calculation software Pandat and thermodynamic database for Mg alloys. The calculated phase diagrams were compared with the key experimental results of DSC analysis for the alloys Mg–1 wt%Gd–7 wt%Y and Mg–5 wt%Gd–2 wt%Y. The solidification and precipitation process of the newly developed alloy Mg–12 wt%Gd–4 wt%Y–0.6 wt%Zr were analyzed. The detailed comparison strongly supports the reliability of the selected thermodynamic description based on the results of thermodynamic calculation. It is clarified that when the Mg–1Gd–7Y alloy ends its solidification and cools down continuously, the second phase Mg 24 Y 5 firstly precipitated from solid solution of magnesium and then the GdMg 5 phase precipitated at relative lower temperature. But for Mg–5Gd–2Y alloy, the precipitation sequence of Mg 24 Y 5 and GdMg 5 are in reverse order. Referring the calculated Mg–Gd–Y system phase diagrams, the suitable thermal mechanical processing and heat-treatment processes of newly designed and developed alloy Mg–12 wt%Gd–4 wt%Y–0.6 wt%Zr has been done.

Precipitation process and its effect on the Vickers hardness, room temperature tensile properties of Mg–9Gd–3Y–0.6Zn–0.5Zr (GWZ930) alloy were investigated in combination with differential scanning calorimetric (DSC), transmission electron microscopy (TEM), Vickers hardness and room temperature tensile test. A four-stage precipitation sequence of supersaturated Mg solid solution, Mg(SSSS) → β″ (144 °C) → β′ (240 °C) → β1 (276 °C) → β (stable), was analyzed. A satisfied combination of high rupture tensile strength and ductility was obtained when the alloy was aged at 200 °C for 63 h post extrusion. Moreover, the effective strengthening mechanisms were explicitly considered and the model prediction strength of GWZ930 alloy was proposed. It is concluded that precipitate strengthening due to the sub-micron metastable phases of β″ and β′ was the largest contributor to the room temperature tensile strength of the alloy GWZ930.

In this work, the static corrosion behaviors of Fe(Al), and 20 wt.% Al2O3/Fe(Al) composites with and without 4 wt.% Cr produced by mechanical alloying (MA) and plasma activated sintering (PAS) were investigated. The results showed that the main corrosion failure mode was pitting, and Fe(Al) had higher static corrosion resistance than those of Al2O3/Fe(Al) composites. The second phase Al2O3 addition resulted in an increase in phase interface and a large difference of the electron density between the Fe(Al) matrix and Al2O3 reinforcement. All these made the phase interface become the corrosion weaknesses. With 4 wt.% Cr addition, the static corrosion weight loss rate reduced by about 20% because Cr element could improve the stability of Al2O3 passivation film on the composite surface.

In this work, Al/SiC composite coatings were deposited on the surface of aluminum alloys through atmospheric plasma spray. The effects of SiC volume in Al/SiC composite powders on the deposition behavior and the properties of the Al/SiC coatings were investigated. It was found that there were decarburization and oxidation during the deposition of pure SiC powders in the plasma flame. With the increase of SiC content, the deposition of the Al/SiC composite powder became more difficult through plasma spray. There were cracks between pure SiC and the bond coat on the Al alloy substrate resulting in poor adhesion between them. The hardness of the composite coating became higher with the increase of SiC contents. The Al/SiC(50:50) deposit with a thickness of 70 µm and a hardness of 369 Hv resulted in a strengthening and protection on the surface of Al alloy.