Mechanism of the Fe3(B,C) and Fe23(C,B)6 solid-state transformation in the hypoeutectic region of the Fe-C-B system
Mechanism of the Fe3(B,C) and Fe23(C,B)6 solid-state transformation in the hypoeutectic region of the Fe-C-B system
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DOI：
10.1016/j.actamat.2016.08.009
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发表时间：
2016-10-15
期刊：
影响因子：
9.4
通讯作者：
Theisen, Werner
中科院分区：
文献类型：
--
作者：
Lentz, Jonathan;Roettger, Arne;Theisen, Werner
研究了铁-碳-硼（Fe-C-B）系亚共晶区Fe-3（B，C）→ Fe-23（C，B）（6）相固态相变的组织机制。从基体相、基体C含量、B/（C + B）比以及母体Fe-3（B，C）相的团聚等方面分析了不同初始组织特征对Fe-3（B，C）→ Fe-23（C，B）（6）相变的影响。我们进行了热力学计算，使用CALPHAD方法，通过实验室熔体不同的B/（B + C）的比例进行验证。这些实验室熔体，然后通过X射线衍射（XRD），扫描电子显微镜（SEM），电子背散射衍射（EBSD），和波长色散X射线光谱（WDS）的微观结构特征。我们特别关注通过原位和非原位XRD测量研究的M-3（C，B）和M-23（C，B）（6）型硼化物和碳硼化物在三元系统Fe-C-B的亚共晶区域中的固态转变。结果发现，固态转变的影响富集B内的共晶组织，凝固的结果。由于硬相结构内B和C的动力学限制，这种增加的B含量在固态下不减少。因此，相稳定性取决于硬相结构的局部C和B浓度的局部平衡。在此过程中，Fe-23（C，B）（6）相还形成围绕Fe-3（B，C）和Fe 2 B相的壳状结构。(C)2016 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
This study investigates the microstructural mechanisms involved in the solid-state transformation of the Fe-3(B,C) -> Fe-23(C,B)(6) phases in the hypoeutectic region of the iron-carbon-boron (Fe-C-B) system. We analyzed the influence of different initial microstructural characteristics on the Fe-3(B,C) -> Fe-23(C,B)(6) transformation with regards to the matrix phase, matrix C content, B/(C + B) ratio, and agglomeration of the parental Fe-3(B,C) phase. We performed thermodynamic calculations using the CALPHAD method, validated by laboratory melts with varying B/(B + C) ratios. These laboratory melts were then micro structurally characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and wavelength-dispersive X-ray spectroscopy (WDS). We particularly focused on solid-state transformation of borides and carboborides of type M-3(C,B) and M-23(C,B)(6) in the hypoeutectic region of the ternary system Fe-C-B, investigated via both in situ and ex situ XRD measurements. It was found that the solid-state transformations are influenced by enriched B inside the eutectic structure, a result of solidification. This increased B content is not reduced in solid state due to the kinetic limitations of B and C inside the hard-phase structure. Thus phase stability is subject to local equilibria depending on the local C and B concentration of the hard-phase structure. In this process the Fe-23(C,B)(6) phase also forms a shell-like structure surrounding the Fe-3(B,C) and Fe2B phases. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.