Orientation relationship of eutectoid FeAl and FeAl(2).
Orientation relationship of eutectoid FeAl and FeAl(2).
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DOI：
10.1107/s1600576716000911
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发表时间：
2016-04-01
影响因子：
6.1
通讯作者：
Heilmaier M
中科院分区：
文献类型：
--
作者：
Scherf A;Kauffmann A;Kauffmann-Weiss S;Scherer T;Li X;Stein F;Heilmaier M
详细研究了共析态FeAl和FeAl2片晶的取向关系和界面，提出了一个结晶学模型。铝含量在55-65 at.%范围内的Fe-Al合金具有B2有序FeAl和三斜相FeAl_2的片状组织，这是由高温Fe_5Al_8相(即所谓的∊相)的共析分解引起的。Bastin等人已经研究了FeAl和FeAl2的取向关系。作者声明：[J.Cryst.Growth(1978)，43,745]和Hirata et al.[Philos.麦格。让我们来吧。(2008)，88,491]。由于这两个结果都基于关于FeAl2的不同结晶学数据，因此根据Chumak等人最近提供的FeAl2相的重新测定，对数据进行了重新评估。作者声明：[Acta Cryst.(2010)，C66，i87]。发现两种取向关系在绕FeAl的〈112FeAl2晶轴旋转180°后或通过应用Chumak数据集所建议的FeAl2晶体结构的反转对称性而匹配。通过取向成像显微镜和整体织构测量，在铸态全片状材料(随机织构)和定向凝固材料(∼〈110〉FeAl||凝固方向)中发现了先前确定的取向关系的有效性的实验证据。此外，通过聚焦离子束截面的径迹分析，确定了FeAl和FeAl2之间的择优界面。基于这些习惯面，两相之间的取向关系可用(01)FeAl||(114)和[111]FeAl||[10]来描述。没有证据表明FeAl片层内存在孪晶，也没有FeAl片层取向交替的证据。基于所确定的取向和界面数据，导出了Fe5Al8、FeAl和FeAl2在共析分解附近的结构关系的原子模型。该模型是根据FeAl和FeAl2界面上的应变进行分析的。
The orientation relationship and interface plane of eutectoid FeAl and FeAl2 lamellae are investigated in detail and a crystallographic model is proposed. Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2.