Journal of Advanced Materials in Engineering (Esteghlal)

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In this paper, a Schwarz-Christoffel method for generating two-dimensional grids for a variety of complex internal and external flow configurations based on the numerical integration procedure of the Schwarz-Christoffel transformation has been developed by using Mathematica, which is a general purpose symbolic-numerical-graphical mathematics software. This method is highly accurate (fifth order) with mesh size, and is highly flexible for treatment of complex internal flow geometries, for a high degree of control of mesh spacing, and for generation of either orthogonal or non-orthogonal grids. In addition, this method directly generates two-dimensional incompressible potential flow solutions for internal flow, and simply or symmetrical multiply connected external flows: it generates a C type grid for a general multiply connected two-dimensional external flow. The capabilities of this method has been shown by sample cases including external flow over symmetric and antisymmetric airfoils, a car profile, and internal flows with arbitrary shapes. To facilitate further applications, a computer program using Mathematica software has been developed.

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In this study, centrifugal casting process was used for producing Al/Mg bimetal. Molten Mg was poured at 700 ^oC, with 1.5 and 3 melt-to-solid volume ratio (Vm/Vs) into the 450 ^oC preheated solid Al rotating at 800, 1200, 1600 and 2000 rpm. Castings were kept inside the centrifuged casting machine and cooled down to 150 ^oC. Investigating the effect of melt-to-solid volume ratio showed that increasing volume ratio from 1.5 to 3 results in diminishing metallurgical bonding in Al/Mg interface, because the force of contraction overcomes the resultant force acted on the interface. The results of study by scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) showed that bimetal compounds of Al₃Mg₂, Al₁₂Mg₁₇ and δ+Al₁₂Mg₁₇ eutectic structure (δ is the solid solution of Mg in Al) are formed in the interface. Atomic force microscopy (AFM) image of Al surface showed that the surface was rough in atomic dimentions, which can result in the formation of gas pores in the interface.