Increasing the oxidation resistance of γ-TiAl by applying a magnetron sputtered aluminum and silicon based coating
Increasing the oxidation resistance of γ-TiAl by applying a magnetron sputtered aluminum and silicon based coating
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DOI：
10.1016/j.intermet.2021.107177
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发表时间：
2021-03-11
期刊：
影响因子：
4.4
通讯作者：
Swadzba, Radoslaw
中科院分区：
文献类型：
--
作者：
Bauer, Peter-Philipp;Laska, Nadine;Swadzba, Radoslaw
在这项研究中，磁控溅射Al-18Si（at. %）研究了一种γ-TiAl基TNB-V2合金的抗氧化涂层。用X射线衍射、扫描电镜和透射电镜研究了涂层的显微组织及其在沉积过程、后热处理和等温氧化试验中的变化和不同相的演变.涂层结合良好，在Al基体中提供了均匀、致密和无裂纹的Si晶粒结晶组织.在550摄氏度下进行20小时后热处理期间的相演变分析以及原位X射线衍射揭示了由于来自TNB-V2基底的Ti和来自涂层的Al的反应而完全形成了TiAl 3相。在850 ℃下氧化300小时期间，形成热生长的α-Al 2 O 3层，提供优异的抗氧化性。α-Al 2 O 3的形成依赖于TiAl 3的存在，而硅充当Ti的吸气剂，因此可以防止TiO 2的形成。此外，最终形成的Ti5Si3相减少了Al向基体中的向内扩散，并防止涂层中Al的快速耗尽。此外，分层涂层微观结构，由具有Ti5Si3相的网络状结构的TiAl3基体组成，在机械性能方面可能是有益的。
In this study, the suitability of a magnetron sputtered Al-18Si (at.%) coating as oxidation protection for a gamma-TiAl based TNB-V2 alloy was investigated. The coating microstructure and its changes as well as the evolution of the different phases during the different steps, deposition process, post heat treatment and isothermal oxidation test, was studied using x-ray diffraction as well as scanning and transmission electron microscopy.The well adherent coating provides a homogenous, dense and crack free crystalline microstructure of Si grains in an Al matrix. The phase evolution analysis during a 20 h post-heat treatment at 550 degrees C with in situ x-ray diffraction reveals the complete formation of the TiAl3 phase due to the reaction of Ti from the TNB-V2 substrate and Al from the coating. During oxidation at 850 degrees C for 300 h, a thermally grown alpha-Al2O3 layer was formed providing excellent oxidation resistance. The formation of alpha-Al2O3 relies on the presence of TiAl3 whereas the silicon acted as a getter for Ti and thus could prevent the formation of TiO2. Furthermore, the finally formed Ti5Si3 phase reduces the inwards diffusion of Al into the substrate and prevents fast Al depletion in the coating. Moreover, the hierarchical coating microstructure, consisting of a TiAl3 matrix with a network-like structure of the Ti5Si3 phase, could be beneficial in terms of mechanical properties.