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This research investigates the effect of Nano-Metal-Phosphate on Si particles through solidification in hypereutectic Al-Si alloys. Which means the merge of modification and refinement with the addition (0.01-0.03) % of Nano-Metal-Phosphate produced by a stir casting. The process synchronizing effects of Nano-Metal-Phosphate that relates to the AlP and Al2O3 formation. These include the following, the effect of Al2O3 at the interfaced between the Al phase and Si particles for obstacle the growth and enhance the refinement of the primary Si and the impact of AlP act as sites of heterogeneous nucleation for eutectic Si. Microstructures analysis revealed that both the fundamental and eutectic Si particles were significantly modified and refined. The primary Si grains were refined from star frames to polygon forms, and their edges were more regular. The platelet eutectic Si grains were also modified into the delicate fibrous forms. Resulting in significant ductility enhancement that could have great potential for numerous applications. Besides, studies microstructure and corrosion behaviour by optical and scanning electron microscopy, XRD and electrochemical cyclic polarization.

Al-13Si alloy microstructure affected by separate additions of Nano-Metal-Phosphate, prepared by die-casting, to synchronize refine eutectic Si and modify eutectic Al is studied. The nucleation and growth mechanisms of the Si phase are discussed via morphology and kinetics analysis. The effects point out that the measurement of eutectic Si is refined to 0.37-2.46 μm and the morphology of the large platelet eutectic Si particles had been modified into the fine fibrous shape. The technique synchronizing consequences of Nano-Metal-Phosphate is related to the AlP and Al2O3 formation. These consist of the following, the impact of Al2O3 at the interfaced between the Al segment and Si particles for obstacle the growth and enhance the refinement of the eutectic Si. The impact of AlP acts to locate of heterogeneous nucleation for eutectic Si, consisting of three aspects: interaction of dopant elements with molten Al-Si alloy to shape the nucleation site with reducing the interface energy between liquid and Si phase and increase the activation of diffusion energy throughout the liquid-solid interface. The results improve the mechanical properties of modified Al-13Si alloy and thus attributed to reducing silicone partials dimension and fibrous structure of eutectic silicon, presence of substantial AlP and Al2O3 in-situ precipitation in the eutectic location and the volume fraction increase of uniform distribution.

In this work, functionally graded AZ91/WC nanocomposites were produced by a novel multi-stage reduction of chamber diameter method. The WC nanoparticles were packed in chambers having graduated diameters and friction stir processing was applied using tool with four-sided fluted probe. The functionally graded nanocomposites were obtained using different tool rotational speeds (830, 960 and 1160 rpm) with a constant traverse speed and plunge depth of 40 mm/min and 0.1 mm, respectively. The characteristics of the functionally graded samples and AZ91 Mg alloy were evaluated utilizing optical and scanning electron microscopes, and energy dispersive spectroscopy as well as other tests such as hardness, pin on disc wear and potentiodynamic polarization tests. The results showed that ?-Mg refining and graded distribution of WC nanoparticles were enhanced with augmenting tool rotational speed. The hardness increased slightly with augmenting tool rotational speed. The results also revealed that the wear rate was decreased and corrosion resistance was improved by adding WC nanoparticles. Abrasive wear mode was the main mode of material removal during dry sliding while cracks and pits were the main features of corroded surface.