Coupled growth zone in Fe-18Cr-C alloys
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REFERENCES 1. Clifford F. Lewis: Materials Engg., May 1986, pp. 33-37. 2. A.A. Das and S. Chatterjee: The Metallurgist and Materials Technologist, March 1981, pp. 137-42. 3. B.F. Quigley, G.J. Abbaschian, R. Wunderlin, and R. Mehrabian: MetalL Trans. A, 1982, vol. 13A, pp. 93-100. 4. B.C. Pai, P.K. Rohatgi, and S. Venkatesh: Wear, 1974, vol. 30, pp. 117-25. 5. A. Banerjee, S. V. Prasad, M. K. Surappa, and P. K. Rohatgi: Wear, 1982, vol. 82, pp. 141-51. 6. A. Mortensen, M.N. Gungor, J.A. Cornie, and M.C. Flemings: J. Metals, 1986, vol. 38, no. 3, pp. 30-35. 7. B.P. Krishnan and P.K. Rohatgi: Metal. Tech., 1984, vol. II, pp. 41-44. 8. B.P. Krishnan, M.K. Surappa, and P.K. Rohatgi: J. Mater. Sci., 1981, vol. 16, pp. 1209-16. 9. M.D. Hanna, Shu-Zu Lu, and A. Hellawell: Metall. Trans. A, 1984, vol. 15A, pp. 459-69. 10. K. E Kobayashi and L.M. Hogan: J. Mater. Sci., 1985, vol. 20, pp. 1961-75. 11. D.C. Jenkinson and L.N. Hogan:'J. Cryst. Growth, 1975, vol. 28, pp. 171-87. 12. R. Elliott: Mater. Sci. and Engg., 1984, vol. 65, pp. 85-92. 13. J.L. Murray and A. J. McAlister: Metal Progress, Dec. 1985, pp. 38 and 43. 14. S. M.D. Glenister and R. Elliott: Metal Science, April 1984, pp. 181-84.
METALLURGICALTRANSACTIONS A
Coupled Growth Zone in Fe-18Cr-C Alloys EDWARD FRAS, HUGO E LOPEZ, and ADAM LISZKA Solidification conditions needed for the production of in situ composites are frequently described by the concept of coupled growth of eutectic phasesJ ~'2m In Fe-C alloys containing 18 wt pct chromium these conditions are not known despite their importance in the development of modem alloys. Although there are reports [4-71 on the structural characteristics and mechanical properties of directionally solidified Fe-Cr-C alloys ta'Sj and other alloy systems such as the Fe-Cr-Mn-C t6'Tjor Fe-Cr-Co-C I51 systems, the range of compositions and the solidification conditions which give a fully eutectic microstructure have not been completely described. This work was carded out to define zone coupled growth conditions in Fe-C alloys containing 18 wt pct Cr. The alloys were produced from Armco iron, chromium of commercial purity (99.8 wt pct), and graphite electrodes of spectral purity. The alloys were prepared in a vacuum induction furnace, and the bath was homogenized at 1450 ~ Quartz tubes were used to extract the liquid metal, and solid bars of approximately 8 mm in diameter were obtained. These alloys were subsequently unidirectionally solidified using rates of displacement of 30 to 3000/zm/s and a temperature gradient in the liquid facing the solidification front of 180 ~ After unidirectional solidification different microstructures were obtained (Figure 1). For the alloys with a eutectic structure produced under a plane front of solidification, chemical analyses were made and conditions for a coupled growth zone were established, as shown in Figure 2. For the carbon contents and rates of growth shown in this figure, the structure in region I consisted of primary carbides ( F e , Cr)7C 3 and the (Fe, Cr)TC 3 + 'y eutectic (Figur
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