New insights into high-temperature deformation and phase transformation mechanisms of lamellar structures in high Nb-containing TiAl alloys
New insights into high-temperature deformation and phase transformation mechanisms of lamellar structures in high Nb-containing TiAl alloys
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DOI：
10.1016/j.actamat.2020.01.021
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发表时间：
2020-03-01
期刊：
影响因子：
9.4
通讯作者：
Pyczak, Florian
中科院分区：
文献类型：
--
作者：
Song, Lin;Appel, Fritz;Pyczak, Florian
研究了高铌TiAl合金高温压缩变形过程中的组织演变。该论文扩展了之前的出版物Song，et al. Intermetallics 109（2019）91-96]，其中报道了α（2）（Ti 3Al）相中独特的孪晶状形态。然而，这些结构的起源无法毫无疑问地澄清。本研究的重点是相变，在这种多相合金可以与变形。特别注意α（2）相到O相或共相关相的局部转化，由于这些相与α（2）的结构和化学相似性，其可以容易地发生并且可以被错误地认为是孪晶结构。所涉及的原子过程的细节通过电子显微镜来阐明。考虑到这种孪生系统的操作所需的大的洗牌和原子位置互换，可以得出结论，α（2）相的孪生是一个扩散位移过程。在α（2）相中，ω（o）是不均匀成核的。裸化位点是缺陷丰富的区域，其经受高局部应力。该研究强调了多相钛铝合金高温变形和相变之间的密切关系。(C)2020 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
The paper describes the microstructure evolution by high-temperature compression of a high Nb-containing TiAl alloy. The paper extends a previous publication Song, et al. Intermetallics 109 (2019) 91-96], in which a unique twin-like morphology in the alpha(2) (Ti3Al) phase was reported. However, the origin of these structures could not be clarified without doubt. The present study is focused on phase transformations that in this multiphase alloy can be associated with deformation. Particular attention is paid to local transformations of the alpha(2) phase into O phase or co-related phases, which, because of structural and chemical similarity of these phases with alpha(2), can easily occur and could mistakenly be considered as a twin structure. The details of the atomic processes involved are elucidated by electron microscopy. Given the large shufflings and the atomic site interchanges required for the operation of this twinning system, it is concluded that twinning of the alpha(2) phase is a diffusive-displacive process. Within the alpha(2) phase, omega(o) is heterogeneously nucleated. The nudeation sites are defect-rich areas, which are subjected to high local stresses. The study strongly emphasizes the close relationship between high-temperature deformation and phase transformations in multiphase titanium aluminide alloys. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.