The effect of aluminium on twinning in binary alpha-titanium
The effect of aluminium on twinning in binary alpha-titanium
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DOI：
10.1016/j.actamat.2015.09.048
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发表时间：
2016-01-15
期刊：
影响因子：
9.4
通讯作者：
Preuss, Michael
中科院分区：
文献类型：
--
作者：
Fitzner, Arnas;Prakash, D. G. Leo;Preuss, Michael
用原位加载和中子衍射相结合的方法，结合事后详细的电子背散射衍射分析，研究了二元Ti-Al模型合金(0-13.1at.%Al)的变形机制。在压缩试验中，所有促进拉伸孪晶的合金都产生了一致的起始晶粒度和织构。用长波中子衍射和选区衍射透射电子显微镜分析了Al有序和Ti3Al形成的证据。结果表明，随着钛中铝含量的增加，孪晶略有增加，其中以{10(1)/bar2}拉伸孪晶为主，而孪晶萌生的临界晶间应变减少。这表明，铝降低层错能或其固溶体强化作用是重要因素。在铝含量约为7at.%时，注意到孪晶活性的转折点，铝含量的进一步增加确实导致孪晶活性的显著丧失，特别是当材料暴露在额外的低温时效时。孪晶活性的急剧下降与短程有序化的证据增加以及在铝含量最高的情况下形成Ti3Al的早期迹象密切相关。此外，电子背散射衍射分析表明，铝有序带的形成确实严重阻碍了孪晶界的生长。(C)2015由Elsevier Ltd.出版的材料学报。这是CC下的一篇开放获取文章，作者为
The deformation mechanisms of binary Ti-Al model alloys (0-13.1 at.% Aluminium) have been investigated with respect to the twinning activity using in-situ loading in combination with neutron diffraction as well as detailed post mortem electron backscatter diffraction analysis. A consistent starting grain size and texture was generated for all alloys promoting tensile twinning during compression testing. Longwavelength neutron diffraction and selected area diffraction transmission electron microscopy analysis were carried out to detect evidence of Aluminium ordering and Ti3Al formation. It was found that raising the Aluminium content in Titanium does first slightly enhance twinning, with {10 (1) over bar2} tensile twinning being by far the dominant type, while the critical residual intergranular strains for twin initiation decreases. This suggests that either the lowering of stacking fault energy by Aluminium or its solute solution strengthening effect are important factors. At around 7 at.% Aluminium a turning point in twinning activity was noticed and a further increase in Aluminium did result in a dramatic loss of twinning activity particularly when the material had been exposed to an additional low temperature age. The dramatic decrease of twinning activity is strongly correlated with increasing evidence of short range ordering and also early signs of Ti3Al-formation in case of the highest Aluminium content. In addition, electron backscatter diffraction analysis revealed that the formation of Aluminium ordered zones do severely hinder growth of twin boundaries.(c) 2015 Acta Materialia Inc. Published by Elsevier Ltd. This is an open access article under the CC BY