Microstructure characterization of a pressureless infiltrating oxidized SiCp preform by Al-8Mg

Abstract

The microstructure of a pressureless infiltrating 55vol% oxidized SiC preform by Al-8Mg alloy was characterized by transmission electron microscopy (TEM), high resolution TEM (HRTEM), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction. The TEM image of the interface between Al and SiC shows that the surface of SiC is covered by a rough nanocrystal layer of MgAl₂O₄, Al₂O₃, and Si, produced by the interfacial reaction of Al, Mg, and SiO₂ on the surface of SiC. The Al-SiC interface is also examined by HRTEM to be better understood how MgAl₂O₄ and Al₂O₃ are produced. Dendritic Al₂O₃ crystals are embedded in the pores of the composite generated from the mutual bonding of SiO₂ on the surface of SiC. Columnar AlN crystals of about 250 nm in length are bunched vertically on the SiC particle surface.

Keywords

microstructure / composites / interfaces / pressureless infiltration / oxidation

References

[1] Pech-Canul M.I., Katz R.N., Makhlouf M.M. Optimum conditions for pressureless infiltration of SiCp preforms by aluminum alloys. J. Mater. Process. Technol., 2000, 108(1): 68.

[2] Aghajanian M.K., Rocazella M.A., Burke J.T., et al. The fabrication of metal matrix composites by pressureless infiltration technique. J. Mater. Sci., 1991, 26(2): 447.

[3] Hashim J., Looney L., Hashmi M.S.J. The wettability of SiC particles by molten aluminium alloy. J. Mater. Process. Technol., 2001, 119(1–3): 324.

[4] Lee J.C., Byun J.Y., Park S.B., et al. Prediction of Si contents to suppress the formation of Al₄C₃ in the SiCp/Al composite. Acta Mater., 1998, 46(5): 1771.

[5] Carotenuto G., Gallo A., Nicolais L. Degradation of SiC particles in aluminium-based composites. J. Mater. Sci., 1994, 29(19): 4967.

[6] Narciso J., García-Cordovilla C., Lowis E. Reactivity of thermally oxidized and unoxidized SiC particulates with aluminium-silicon alloys. Mater. Sci. Eng. B, 1992, 15(2): 148.

[7] Luo Z.P., Song Y.G., Zhang S.Q. A TEM study of the microstructure of SiCp/Al composite prepared by pressureless infiltration method. Scripta Mater., 2001, 45(10): 1183.

[8] Lee J.C., Ahn J.P., Shim J.H., et al. Control of the interface in SiC/Al composites. Scripta Mater., 1999, 41(8): 895.

[9] Shi Z., Ochiai S., Gu M., et al. The formation and thermostability of MgO and MgAl₂O₄ nanoparticles in oxidized SiC particle-reinforced Al-Mg composites. Appl. Phys. A, 2002, 74(1): 97.

[10] Honig J.M. Thermodynamics, 1980 West Lafayette, Purdue University, 1025.

[11] Brook R.J., Cahn R.W., Bever M.B. Concise Encyclopedia of Advanced Ceramic Materials Advances in Materials Science and Engineering, 1991 U.K., Pergamon Press, 145.

[12] Gu M.Y., Mei Z., Jin Y.P., et al. Structure and amorphization of the oxide on the silicon carbide surface in an SiCp/Al composite. Scripta Mater., 1999, 40(9): 985.

[13] Shen X.Y., Ren S.B., He X.B., et al. Study on methods to strengthen SiC preforms for SiCp/Al composites by pressureless infiltration. J. Alloys Compd., 2009, 468(1–2): 158.

[14] Scholz H., Greil P. Nitridation reactions of molten Al-(Mg, Si) alloys. J. Mater. Sci., 1991, 26(3): 669.

[15] Urena A., Martinez E.E., Rodrigo P., et al. Oxidation treatments for SiC particles used as reinforcement in aluminium matrix composites. Compos. Sci. Technol., 2004, 64(12): 1843.