本研究探討四元鐵-12.5錳-6.53鋁-1.28碳合金鋼的相變化情形。合金鋼經固溶處理及後續的低溫熱處理後，其內產生至少三種不同的相變化。首先為r’相析出反應：當合金鋼經固溶處理與空冷後，發現非常細小的r’晶粒均勻地分佈於沃斯田體基地內。此種相變化的反應方式如下：於空氣冷卻的過程中，r’相以整合析出的方式，於沃斯田體晶粒內均勻的分佈。第二類的相變化形式為K-碳化物的析出反應：合金於875℃以下溫度，過飽和沃斯田體相會經由析出反應，藉由K-碳化物的析出，而成為低溫穩定的沃斯田體與K-碳化物；晶界K-碳化物與(r + K)層狀組織為其反應生成組織。於研究(r + K)層狀組織時，發現於K-碳化物的層狀晶粒旁，常伴隨有層狀沃斯田體雙晶；此種層狀雙晶的附著在K-碳化物的層狀晶粒的週圍，其可能原因為降低層狀K-碳化物晶粒析出於沃斯田體基地時的活化能，而使反應速率增加。第三類的相變化為共析反應：於700℃以下時，過飽和沃斯田體會經由共析反應而分解為低溫穩定的K-碳化物與肥粒體的似波來體組織。

Three types of low-temperature phase transformations in an Fe-12.5 Mn-6.53 Al-1.28 C (wt%) alloy have been studied. The steel underwent solution heat treatment at 1100℃ and isothermal holding at low temperatures. r’ phase appears in the austenite matrix in the air-cooled steel. Coherent ultra-fine particles of r’ phase precipitated uniformly in the austenite matrix after the air-cooling process. These ultra-fine particles were very small and only could be detected by TEM through dark-field images. After short periods of isothermal holding at low temperatures these particles of r’ phase grew and could be easily detected by TEM. A pro-eutectoid reaction happened after isothermal holding at temperatures below 875℃. Proeutectoid K-carbide and ferrite appear in the austenite matrix as grain boundary precipitates and cellular precipitates. The cellular precipitates are composed of lamellar K-carbide and austenite. The lamellar K-carbide grains are always accompanied by layers of austenite twins. The presence of twin layers adhering to the K-carbide plates might be attributed to the lower activation energy for the precipitation of K-carbide plates in the austenite. The final form of phase transformation is the eutectoid reaction for the decomposition of supersaturated austenite into stable K-carbide and ferrite phases at temperatures below 700℃. The ferrite and K-carbide are in the form of pearlite lamellae.

1. H.V. Lawrence, Elements of Materials Science and Engineering, 6th ed., Addison Wesley(1995).
2. R.E. Reed-Hill, Physical Metallurgy Principles, 3rd ed., pp.538-585 (1992).
3. W.F. Smith, Structure and Properties of Engineering Alloys, 2/e, pp1-25 (1993).
4. C.R. Huchinson, R.E. Hackenberg, G.J. Shiflet, Acta Mat. 52, 3565 (2004).
5. C.R. Huchinson and G.J. Shiflet, Scripta Meterialia., 50, 1 (2004).
6. S.A. Hackey and G.J. Shiflet, Acta Metall., 35, 1017 (1987).
7. S.A. Hackey and G.J. Shiflet, Scripta Metal., 19, 757 (1985).
8. D.S. Zhou, G.J. Shiflet, Scripta Metallurgica., 27, 1215 (1992).
9. 張容，““10錳高錳鋼低溫相變化研究”，國立台灣科技大學機械工程研究所，碩士論文(2011)。
10. 許中杰，“鐵-20錳-4鋁-0.5碳合金鋼之時效相變化研究”，國立台灣科技大學機械工程研究所，碩士論文 (2008)。
11. Y.L. Lin, C.P. C.P. Chou, Scripta Metall., 27, 67 (1992).
12. 蘇文淵，“鐵-30.1錳-4鋁-0.64碳合金鋼之時效相變化研究”，國立台灣科技大學機械工程研究所，碩士論文 (2009)。
13. 張育仁，““鐵-30錳-1.7鋁-1碳合金鋼之時效相變化研究”，國立台灣科技大學機械工程研究所，碩士論文 (2009)。
14. M.C. Li, H. Chang, P.W. Kao, Mat. Chem. Phys., 5996 (1999).
15. K.H. Han, J.C. Yoon, W.K. Choo, Scripta Metall., 20, 33 (1986).
16. Y.G. Kim, Y.S. Park and J.K. Han, Metall. Trans. A, 16, 1689 (1985).
17. Y.G. Kim, J.K. Han and E.W. Lee, Metall. Trans. A, 17, 2097 (1986).
18. D.A. Porter and K.E. Easterling, “Phase Transformations in Metals and Alloys”, 3rd (2008).
19. P.M. Kelly and M.X. Zhang, Acta Mater., vol. 46, no. 13, 4617 (1998).
20. 陳致豪，“鐵-30錳-0.3碳合金鋼之時效相變化硏究”，國立台灣科技大學，碩士論文 (2009)。
21. 鍾榕晏，“含20錳的高錳鋼相變化研究””，國立台灣科技大學，碩士論文 (2011)。
22. W.K. Choo and K.H. Han, Metall. Trnans. A, 16 5 (1985).
23. G. Krauss, Principles of Heat Treatment of Steel, ASM, pp.17-41, (1980).
24. E.C. Bain and H.W. Paxton, Alloying Elements in steel, 2nd ed., American Society for Metals, pp. 18 (1966).
25. 陳崧豪，“鐵-20錳-2鋁合金鋼之相變化研究”，國立台灣科技大學機械工程研究所，碩士論文 (2008)。
26. 薛凱云，“鐵-12錳-4鋁-0.5碳合金鋼之亞共析型反應研究”，國立台灣科技大學機械工程研究所，碩士論文 (2007)。
27. 黃祥銘，“鐵-13錳-3鋁-0.5碳合金鋼共析反應研究”，國立台灣科技大學機械工程研究所，碩士論文 (2010)。
28. 吳旻紘，“鐵-31錳-1.5鋁-0.6碳合金鋼之時效相變化研究”，國立台灣科技大學機械工程研究所，碩士論文 (2009)。
29. K.H. Hwang, C.M. Wan, J.G. Byrne, Mat. Sci Eng. A, 132, 161 (1991).
30. R. C. Ecob, J. V. Bee and B. Ralph, The structure of the β-phase in dilute copper–titanium alloys physica status solidi (a) , volume 52, Issue 116 March 1979, Pages: 201–210(1979).
31. Roger C. Ecob, John V. Bee and Brian Ralph, Some Microstructural Observations Of Transformations In A Copper-Titanium Alloy (pages 141–150) (1979).
32. R. C. Ecob, J. V. Bee and B. Ralph, The cellular reaction in dilute copper-titanium alloys Met. trans. 11A, 1407(1980).