鐵-8鋁-15錳-1矽-0.4碳合金相變化

The Phase Transformations of the Fe-8Al-15Mn-1Si-0.4C Alloy

林義傑(Yi-chieh Lin)

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(2008年)

https://doi.org/10.6346/NPUST.2008.00217

摘要

本文主要係利用光學顯微鏡(OM)與穿透式電子顯微鏡(TEM)等分析技術，針對鐵-8鋁-15錳-1矽-0.4碳合金相變化進行研究分析。主要研究結果顯示，合金經1100℃持溫30分鐘之固溶處理後，其顯微結構主要為(沃斯田鐵相+肥粒鐵相)，其中沃斯田鐵相區為單相結構，肥粒鐵相區為(α+B2+ DO3)之混合區域，而(α+B2+DO3)是高溫淬火過程中，經由連續規則化所產生。
合金經200℃~650℃不等時間之時效處理後，沃斯田鐵區並無觀察到κ相析出，其肥粒鐵相區有針狀L12結構析出物產生，其中DO3相沿<100>方向成長。當時效溫度提高至750℃，γ相雙晶處會有具L12結構析出物產生。因此合金經200℃~750℃其相變化過程為(α+DO3+B2+針狀L12結構析出物)→(α+顆粒狀DO3+針狀L12結構析出物)→(α+方塊狀DO3+針狀L12結構析出物) →(α+ B2)。此外在時效過程中，在α/γ晶界上觀察到α相會沿著[012] α方向成長。

關鍵字

鐵鋁錳碳矽合金 ； DO3相 ； 顯微結構 ； 穿透式電子顯微鏡

並列摘要

The main purposes of the present studies are to investigate the phase transformations of the Fe-8Al-15Mn-1Si-0.4C alloy by using optical microscopy (OM) and transmission electron microscopy (TEM). The microstructure of the alloy after being solution heat-treated at 1100℃ for 30 min and then quenched. It reveals a (γ+α) phase microstructure. The austenite matrix was single-phase and the ferrite matrix were (α+B2+DO3) phases microstructure, where the (α+B2+DO3) were formed by a continuous ordering transition during quenching.
When the as-quenched specimen aged at the temperature from the 200℃~650℃ for longer times, no evidence of the (Fe,Mn)3AlCx carbides formed on the austenite matrix could be detected. Moreover, the needle-like precipitates has L12-type structure occurred as well as the DO3 precipitates grew along <100> directions on the ferrite matrix on the α matrix. When the aging temperature was increased to 750℃ for shorter times, a needle-like L12-type precipitates occurred on the twin boundary of austenite matrix. With increasing the aging temperatures from 200℃ to 750℃, the phase transformation sequence occurring within the α matrix is found to be (α+DO3+B2+needle-like L12-phase)→(α+ spherical DO3+ needle-like L12- phase)→(α+ quadrate DO3+ needle-like L12-phase) →(α+ B2). Furthermore, during aging, the ferrite grains grew along <100> directions to the austenite matrix on the γ/α grain boundary.

並列關鍵字

Fe-Al-Mn-C-Si alloy ； DO3-phase ； microstructure ； transmission electron microscopy

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