STUDY ON GRANULATION MECHANISMS OF γ+(Fe,Mn)3C EUTECTICS IN AUSTENITE STEEL COMPOSITES
来源期刊：Acta Metallurgica Sinica2003年第6期
论文作者：G.F.Liang Q.C.Jiang J.G.Li Z.M.Xu
Key words：composite; RE-Mg agent; granulation; unidirectional solidification;
Abstract: Results presented in this paper contribute to investigation of the granulation mechanisms of γ+(Fe, Mn)3C eutectics in the austenite matrix composites (abbreviated EAMC). The specimens corresponding to the nominal composition of eutectic with controlled RE(Ce)-Mg agent modifier additions have been unidirectional solidified with a constant growth rate of 2.18μm/s at a fixed temperature gradient of 800K/cm using vertical Bridgeman method. With the RE-Mg agent modifier, the transition of solid/liquid (S/L) interface from columnar to dendrite (CDT), refinement and developed branching of γ and (Fe, Mn)3C phases in the eutectics, and the transition of growth style from faceted-nonfaceted (F/NF) to nonfaceted-nonfaceted (NF/NF)for γ and (Fe, Mn)3C phases in the eutectic have been observed and investigated theoretically. Those can explain the granulation of γ+(Fe, Mn)3C eutectics in the as cast because the roundness increases with the developed lateral branching of primary austenite dendrites, refinement of eutectics, and NF/NF growth of γ and (Fe,Mn)3 C phases in the eutectic.
G.F.Liang1，Q.C.Jiang2，J.G.Li1，Z.M.Xu1
(1.School of Materials Science and Technology, Shanghai Jiaotong University, Shanghai 200030, China;
2.School of Materials Science, Jilin University, Changchun 130025, China)
Abstract:Results presented in this paper contribute to investigation of the granulation mechanisms of γ+(Fe, Mn)3C eutectics in the austenite matrix composites (abbreviated EAMC). The specimens corresponding to the nominal composition of eutectic with controlled RE(Ce)-Mg agent modifier additions have been unidirectional solidified with a constant growth rate of 2.18μm/s at a fixed temperature gradient of 800K/cm using vertical Bridgeman method. With the RE-Mg agent modifier, the transition of solid/liquid (S/L) interface from columnar to dendrite (CDT), refinement and developed branching of γ and (Fe, Mn)3C phases in the eutectics, and the transition of growth style from faceted-nonfaceted (F/NF) to nonfaceted-nonfaceted (NF/NF)for γ and (Fe, Mn)3C phases in the eutectic have been observed and investigated theoretically. Those can explain the granulation of γ+(Fe, Mn)3C eutectics in the as cast because the roundness increases with the developed lateral branching of primary austenite dendrites, refinement of eutectics, and NF/NF growth of γ and (Fe,Mn)3 C phases in the eutectic.
Key words:composite; RE-Mg agent; granulation; unidirectional solidification;
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