鐵-9鋁-28錳-20鈷-1碳合金相變化

Phase Transformations on Fe-9Al-28Mn-20Co-1C Alloy

金衍志(Yan-Chih Jin)

指導教授 ： 趙志燁

國立屏東科技大學/工學院/機械工程系所/碩士(2010年)

https://doi.org/10.6346/NPUST.2010.00086

摘要

本文主要利用光學顯微鏡、掃描式電子顯微鏡、穿透式電子顯微鏡等分析技術，探討20鈷元素添加量對鐵-9鋁-28錳-1碳合金之相變化，主要研究結果如下所示：
在合金固溶方面，合金於1200℃/30分鐘固溶處理後，顯微結構為雙相肥粒鐵與沃斯田鐵，經由穿透式電子顯微鏡觀察顯示，在肥粒鐵基地內觀察(B2+DO3)規律相與針狀的α，而沃斯田鐵基地內可觀察到κ相碳化物。沃斯田鐵晶格常數a=0.364nm，肥粒鐵晶格常數a=0.286nm。在550℃時效處理基地與邊界可發現Co2Al析出物的產生，γ基地產生了(γ+κ→γ+κ’+Co2Al)相變化。時效增加到750℃以上發現顆粒狀Co2Al析出物，到850℃呈現片狀結構。
高含量的鈷元素添加，在顯微結構中1200℃的固溶處理才可得到穩定沃斯田鐵與肥粒鐵的產生，時效過程中有Co2Al析出物於沃斯基地產生，在高溫時效方面相變化呈現DO22，合金相變化[(α+B2+DO3)+(γ+κ)]→[(α+B2+DO3+Co2Al)+(γ+κ’+Co2Al+DO3 )]。

關鍵字

肥粒鐵 ； 沃斯田鐵 ； κ相碳化物 ； Co2Al

並列摘要

The main purposes of the present studies are to investigate the phase transformation of the Fe-9Al-28Mn-20Co-1C Alloy by using optical microscopy, scanning electron microscopy and transmission electron microscopy. The microstructure of the alloy after being solution heat-treated at 1200℃ for 30 min and then quenched. It reveals a (α+γ)phase microstructure. The austenite matrix the κ-phase carbides were found and ferrite matrix were (α+B2+DO3) phase microstructure. The lattice parameter of austenite phase is a=0.364nm, the lattice parameter of ferrite phase is a=0.286nm. When the as-quenched specimen aged at the temperature form the 550℃ for longer time . It reveals a (α+γ)phase microstructure. The Co2Al-phase been observed within the austenite matrix. The phase transformation of γ matrix was found to be (γ+κ→γ+κ’+Co2Al). When the aging temperature was increased to 750℃, Co4Al been observed quadrate structure, and the aging temperature was increased to 850℃, Co2Al been observed flake structure.
When High content Co element increase, the microstructure of the solution heat-treatment in the 1200℃ could been stable austenite and ferrite formation, in the aging process has Co2Al base precipitates produced in the austenite matrix, in the high temperature aging of the phase transformations was DO22 , phase transformations of the alloy [(α+B2+DO3)+(γ+κ)]→[(α+B2+DO3+Co2Al)+(γ+κ’+Co2Al+DO3 )].

並列關鍵字

ferrite ； austenite ； κ-phase carbides ； Co2Al

參考文獻

7. Wei-Chun Cheng﹐Yuan-Ching Lin﹐Chia-Fu Lin﹐2003,“The fracture behaviors in an Fe-Mn-Al alloy during quenching processes” Materials Science and Engineering ,A343, 28－35.

8. R. Umino﹐X.J. Lin﹐Y. Sutou﹐C.P. Wang﹐I.Ohnuma﹐R. Kainuma﹐and K. Ishida﹐2006﹐“Experimental Determination and Thermodynamic Calculation of Phase Equilibria in the Fe-Mn-Al System”﹐J. Phase Equilb. Diffus.﹐27(1)﹐p54－62.

12. Wei-Chun Cheng﹐Chia-Fu Lin﹐Yi-Fan Lai,2002 ,“Dislocation loops and phase decompositions of B2-FeAl(Co) compound in Fe-Al-Co ternary system” Intermetallics ,A10, pp.641－646.

16. Chao, C.Y., Hwang, C.N., and Liu, T.F., 1992,“Grain Boundary Precipitation in An Fe-7.8Al-31.7Mn-0.54C Alloys”, Scripta Metallurgicaet Materialia, pp.109-114.

17. Charles,J., and Berghezan, A., 1981,“Nickel-free Austenitic for” Cryogenic Applications：the Fe-23Mn-5Al-0.2CAlloys”, Cryogenics,pp.278-280.