|標題:||鐵-9.0 鋁-30.0 錳-1.5 矽-2.0碳合金相變化|
Phase Transformation in an Fe-9.0 Al-30.0 Nm-1.5 Si-2.0C Alloy
|摘要:||我們利用光學顯微鏡（OM），穿透式電子顯微鏡（TEM）以及X-光能量散佈分析儀（EDS），研究鐵-9.0鋁-30.OMn-1. 5Si-2. OC合金之相變化。
Phase Transformations in the Fe-9.0Al-30.0Mn-1.5Si-2.0C alloy have been examined by means of optical microscopy (OM), transmission electron microscopy (TEM) and energy-disopersive X-ray spectrometer (EDS). In the as-quenched condition, the microstructure of the alloy was austenite phase containing extremely fine (Fe,Mn)3ALCx (K'-carbides). the K'-carbides having an L'12-type structure were formed within the austenite matrix during quenching by a spinodal decomposition. When the alloy was aged at termperatures ranging from 550℃ to 990℃, the k'-carbides not only existed within the austenite matrix but also on the grain boundaries. The phase transition sequence as the temperature increases was found to be r→DO3 + k-phase→B2 +K-phase→a +K-phase. It is worthy to note that the k'-carbide has an L'l2-type structure at 750℃ or below and an Ll2-type structure at 850℃ or above. when the alloy was aged at 950, both the coarse and extremely fine k' carbides could be observed with the austenite matrix. The coarse k' carbides had occurred at the aging temperature; whereas the extremely fine k' carbides were of formed during quenching by a spinodal decomposition. The coesistence of the coarse and extremely fine k' carbides formed within the austenite matrix has never been observed by other workers in the Fe-Al -Mn-C alloy systems.
|Appears in Collections:||Thesis|