| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 92 === We studied the phase transformations of the Fe-Mn-Al alloys with low Mn contents 4.2 at.%. The Al contents in these alloys are 15.8、18.0、20.0、22.2、24.4 and 26.6 at.% respectively. The heating process are solution at 1000℃ holding 1 hour then quenching in room-temperature water. After the above process, the alloys have been aged in variance temperature for studied. Within FeAl and Fe3Al phases of the six kinds of the Fe-Mn-Al alloys, using the Analysis Electron Microstructure observed phase transformations of the continuous ordering and the traditional nucleation and growth mechanism. According to these results we could judge the shift orientation of a→B2→D03 reaction curves on Fe-Al coherent diagram. The results are the formation temperature of D03 lower and a→D03 reaction curves shift obviously along lower Al contents site variance with Al contents decrease. From two phases FeAl and Fe3Al coexist line which is at about 550℃, the B2→D03 reaction curve shift along higher Al contents site. In Fe-Mn-Al alloys with Mn contents 0.6 at.% , the reaction curve of a→a＋D03 was not obviously out of the original site of Fe-Al coherent diagram along the orientation of lower Al contents.
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