A method of assessing the reactivity between SiC and molten AI
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The authors acknowledge the advice and encouragement of Professors Earl R. Parker and Victor F. Zackay. This work was partially supported by the Office of Energy Research of the United States Department of Energy.
REFERENCES 1. A. Magnee, J.M. Drapier, J. Dumont, D. Coutsouradis, and L. Habraken: Cobalt-Containing High Strength Steels, Centre D'information du Cobalt, Brussels, 1974, ch. 7. 2. G.A. Roberts, J.C. Hamaker, Jr., and A.R. Johnson: Tool Steels, ASM, Metals Park, OH, 1962, chs. 11 and 12. 3. J.A. Rescalvo and B. L. Averbach: Metall. Trans. A, 1979, vol. 10A, pp. 1265-84. 4. H. Johansson and R. Sandstrom: Mat. Sci. and Eng., 1978, vol. 36, pp. 175-80. 5. K. Eriksson: Scand. J. Metall., 1973, vol. 2, no. 4, pp. 197-203. 6. Vasco Company, Matrix Steel, U.S. Patent #3, 117, 863, Vasco, Latrobe, PA 15650, 1964. 7. T.A. Lechtenberg: Ph.D. Thesis, University of California, Berkeley, CA, 1979. 8. W.B. Pearson: Handbook of Lattice Spacings and Structures of Metals and Alloys, Pergamon Press, 1967, vol. 2, p. 127. 9. V. Seetharaman, M. Sundararaman, and R. Krishnan: Mat. Sci. and Eng., 1981, vol. 47. pp. 1-11. 10. G.C. Gould and H.J. Beattie: Trans. TMS-A1ME, 1961, vol. 221, pp. 893-95. 11. R. Blower, R.K. Greenwood, and G.P. Miller: Conference on Low Alloy Steels, ISI Publication 114, The Iron and Steel Institute, London, 1968, p. 119. 12. B. de Miramon: M.S. Thesis, University of Califorma, Berkeley, CA, 1967 (Lawrence Berkeley Laboratory-UCRL-17849). 13. R.M. Horn and R.O. Ritchie: Metall. Trans. A, 1978, vol. 9A, pp. 1039-53. 14. H.J. Rack and D. Kalish: Metall. Trans., 1971, vol 2, pp. 3011-20.
paper we want to consider these two aspects of A1-SiC composites. SiC is thermodynamically unstable in molten A1t~'2j and reacts to form aluminum carbide according to the reaction: 4A1 + 3SiC ~ A14C3 + 3Si
The extent of the reaction has been followed by measuring the intensity of the aluminum carbide and silicon X-ray peaks from the composite. TM The reaction can also be followed by chemical analysis of the composite and, in the case of fiber composites, by measuring the thickness of the fiber-matrix interaction layer. [4] There is an alternative method for those alloys where the influence of Si on the phase diagram is known, and this is determining changes in the liquidus temperature. As the reaction occurs according to Eq. [1], the Si content of the alloy increases and the liquidus temperature decreases in most alloys of interest. In this paper the effect of silicon carbide reaction on the liquidus of an AA6061-20 vol pet SiC particulate reinforced composite is considered. The initial composite was remelted and held for one hour at 675,800, and 900 ~ and then resolidified. The liquidus temperatures of the remelted material were then measured from differential scanning calorimetry (DSC) traces, using a 20 deg per minute heating rate, under argon flowing at 60 ml/min and a specimen size of 15 to 20 mgms. The changes in the A1-Si liquidus temperature with remelt temperature are shown in Figure 1, and as expected the l
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