本論文研究鐵-30.2錳-0.30碳(wt%)之合金經時效處理後的相變化情形。合金先經1100℃的固溶處理，其於1100℃時為單一沃斯田體相，而於冷卻過程中於沃斯田體晶粒內會生成麻田散鐵。當合金再經700℃以下低溫時效處理後，於沃斯田體晶界處有M3C與 M23C6碳化物的析出。M23C6碳化物具複雜面心立方的結晶結構，其晶格常數約為a=1.076 nm。當M23C6碳化物於沃斯田體的晶界處析出時，其與其旁之一的沃斯田體晶體間有立方晶對立方晶之方位關係。而M3C碳化物為斜方晶系，其三軸的晶格常數各為a=0.458、b=0.510及c=0.668 nm。所以M3C與M23C6碳化物等二種碳化物可共同存在於本合金內，此現象於鐵錳碳三元合金是首次被觀察到。
經由EDS的成份分析，發現M23C6碳化物的金屬組成的鐵錳比例約為Fe46.8Mn53.2，M3C碳化物的比例則為Fe49.2Mn50.8，而基地沃斯田體的比例約為Fe75.8Mn24.2；所以M3C及M23C6碳化物等二種碳化物的錳含量皆較沃斯田體基地為高；而M23C6碳化物之錳含量亦較M3C碳化物為高。
本研究發現波來體組織的初始層狀排列晶粒，此為波來體組織的成核成長之初始狀態。推論M3C碳化物先於沃斯田體的晶界處成核，其應與非成長側的沃斯田體晶粒有方位關係，而後往另一側的沃斯田體晶粒內成長；本文發現其旁成核的肥粒體晶粒與非成長側的沃斯田體晶粒具有K-S之方位關係。故初始層狀排列的M3C碳化物及肥粒體晶粒與非成長側的沃斯田體晶粒間皆應有方位關係。

The purpose of this study is to investigate the phase transformations due to aging treatment. The composition of the alloy is Fe-30.2 wt% Mn-0.5 wt% C. When the alloy underwent solution heat treatment at 1100℃, it was composed of austenite grains and wicker-shape precipitates distributed within the austenite. When the alloy underwent aging treatment below 700℃, there were M3C and M23C6 carbides precipitates on grain boundaries within the austenite. The structure of M23C6 carbides is FCC, in which the lattice parameter is about 1.076 nm. When the M23C6 carbide precipitates in the grain boundary of the austenitic matrix, the result shows that the orientation relationship of M23C6 and austenite is cubic to cubic. M3C has an orthorhombic structure with a=0.458, b=0.510, c=0.668nm. M23C6 and M3C carbides can co-exist in the alloy. They are first found together in the Fe-Mn-C ternary system.
By EDS analysis, it is found that the proportions of Fe and Mn in M23C6 are about Fe46.8Mn53.2, and in M3C are Fe49.2Mn50.8 and in austenite are Fe75.8Mn24.2; therefore, the concentrations of Mn in M3C and M23C6 are higher than in austenite and the proportion of Mn in M23C6 is higher than in M3C.
Initial pearlitic lamellae which formed in the first stage of the nucleation and growth of pearlitic structure were observed in this study. It is suggested that M3C nucleate on the grain boundary of austenite at the beginning, which has an orientation relationship with the semi-coherent interface of austenite. Besides, pearlite grows into the austenite grain with which it does not have an orientation relationship. Since ferrite and semi-coherent of austenite have K-S orientation relationship. Consequently, M3C and ferrite have an orientation relationnship with semi-coherent interface of austenite.

1. D.A. Porter and K.E. Easterling, Phase Transformations in Metals and Alloys, 4/e, 314 , Nelson Thornes Ltd. (1992).
2. J. Janovec, M. Svoboda, A. Vyrostkova, A. Kroupa, Materials Science and Eng. A, 402, 288 (2005).
3. J.B. Lupton, S. Murphy and J.H. Woodhead, Metall. Trans., 3, 2923 (1972).
4. B. Weiss R. Stickler, Metall. Trans., 3, (1972).
5. Y.L. Lin and C.P. Chou, Scripta Metall., 27, 67 (1992).
6. W.F. Smith, Structure and Properties of Engineering Alloys, 2/e, pp. 1-25 (1993).
7. M.H. Lewis, B. Hattersley, Acta Metall., 13,1159 (1965).
8. A. Vyrostkova, A. Kroupa, J. Janovec, M. Svoboda, Acta Mater. 46(1), 31 (1998).
9. H. Baker, “ASM Handbook, Vol 3, Alloy Phase Diagrams” (1987).
10. P. Villars, A. Prince, and H. Okamoto, “Handbook of ternary alloy phase diagrams” (1994).
11. U.V. Choudary, Y.A. Chang, Calphad, 2(2), 169 (1978).
12. 許中杰，“鐵-20錳-0.5碳合金鋼之時效相變化研究”，國立台灣科技大學，碩士論文(2008)。
13. 薛凱云，“鐵-12錳-4鋁-0.5碳合金鋼之亞共析型反應研究”，國立台灣科技大學，碩士論文(2007)。
14. G. Krauss, Principles of Heat Treatment of Steel, ASM, 17, (1980).
15. C.R. Hutchinson , G.J. Shiflet, Scripta Mater. 50, 1 (2004).
16. C.R. Hutchinson, R.E. Hackenberg, G.J. Shiflet, Acta Mater. 52, 3565 (2004).
17. H.J. Goldschmidt., Interstitial Alloys, pp 104 (1967).
18. D.S. Zhou, G.J Shiflet, Scripta Metall. Mater., 27, 1215 (1992).
19. M. Vach, T. Kunikova, Material Charact., 59, 1792 (2008).
20. K. Campbell, R. W. K. Honeycombe, Metal Science, 355 (1973).
21. B.D. Cullity, Elements of X-Ray Diffraction 2nd ed., Addison Wesley Publisher (1997).
22. D.B. Williams and C.B. Carter, “Transmission Electron Microscopy”, Plenum (1996).
23. 陳力俊等，“材料電子顯微鏡學”，國科會精儀中心 (1997)。
24. 鮑忠興等，“近代穿透式電子顯微鏡實務”，滄海書局 (2008)。
25. 林東一，“鐵-21錳-0.4碳合金之麻田散體相變化研究”，國立台灣科技大學，碩士論文(2007)。