An effective approach to describe growth of binary intermediate phases with narrow ranges of homogeneity
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This work was supported by POSCO. REFERENCES 1. C.D. Little and P.M. Machmeier: U.S. Patent 4,076,525, 1978. 2. R. Ayer and P.M. Machmeier: Metall. Trans. A, 1993, vol. 24A, pp. 1943-55. 3. R. Ayer and P.M. Machmeier: Metall. Mater. Trans. A, 1996, vol. 27A, pp. 2510-17. 4. C.H. Yoo, H.M. Lee, J.W. Chan, and J.W. Morris, Jr.: Metall. Mater. Trans. A, 1996, vol. 27, pp. 3466-72. 5. G.R. Speich, D.S. Dabkowski, and L.F. Porter: Metall. Trans., 1973, vol. 4, pp. 303-15. 6. G.R. Speich: Innovations in Ultrahigh Strength Steel Technology, Proc. 34th Sagamore Army Materials Research Conf., G.B. Olson, M. Azrin, and E.S. Wright, eds., United States Army Materials Technology Laboratory, Watertown, MA, 1990, pp. 89-110. 7. G.B. Olson: Innovations in Ultrahigh Strength Steel Technology, Proc. 34th Sagamore Army Materials Research Conf., G.B. Olson, M. Azrin, and E.S. Wright, eds., United States Army Materials Technology Laboratory, Watertown, MA, 1990, pp. 3-66. 8. V.K. Chandhok, J.P. Hirth, and E.J. Dulis: Trans. ASM, 1963, vol. 56, pp. 677-93. 9. K.B. Lee, H.R. Yang, and H. Kwon: J. Kor. Inst. Met. Mater., 1995, vol. 33, pp. 1241-49. 10. H. Kwon, C.M. Kim, K.B. Lee, H.R. Yang, and J.H. Lee: Metall. Mater. Trans. A, 1997, vol. 28A, pp. 621-27. 11. H. Kwon, C.M. Kim, K.B. Lee, H.R. Yang, and J.H. Lee: Metall. Mater. Trans. A, 1996, vol. 27A, pp. 3343-46. 12. H. Kwon, C.M. Kim, K.B. Lee, H.R. Yang, and J.H. Lee: Metall. Mater. Trans. A, 1998, vol. 29A, pp. 397-401. 13. K.B. Lee, S.M. Kang, H. Kwon, H.R. Yang, S.Y. Cho, and C.M. Kim: Proc. Symp. ’96 on Mechanical Behavior of Materials, Korean Institute of Metals and Materials, Seoul, Korea, 1996, pp. 221-30. 14. H.R. Yang, K.B. Lee, and H. Kwon: Mater. Sci. Eng. A, 1999, vol. 265, pp. 179-87. 15. Y. Oh, P.M. Machmeir, T. Matuszewski, and R. Ayer: J. Mater. Eng. Performance, 1997, vol. 6, pp. 289-99. 16. P.M. Machmeir, T. Matuszewski, R. Jones, and R. Ayer: J. Mater. Eng. Performance, 1997, vol. 6, pp. 279-88. Fig. 6—TEM micrograph, showing undissolved carbides in the martensitic structure, and EDS spectra of (a) matrix and (b) undissolved carbide for the 12Ni steel austenitized at 875 ⬚C.
Figure 6 shows undissolved carbides and corresponding energy-dispersive spectroscopy (EDS) spectra reflecting the relative amounts of the existing elements. It is noted that the WL peak appears much smaller than the CrK peak even at a similar weight percent. The undissolved carbides contained significant amounts of W, several times the amount of Cr (weight percent), even though the W/Cr ratio is near unity (weight percent) in the steels (Table I). This result means that the Cr/W ratio in the matrix was, in turn, increased, as shown in the EDS analysis of the matrix. It is believed that the increase of the Cr/W ratio in the matrix results in the acceleration of aging even though the mechanism is not clear. At present, it is considered that the nucleation and growth of the M2C carbides may be promoted through the compositional and structural modifications, resulting from the increase in Cr/W r
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