Guo Chunyu, Wang Enhui, Liu Yunsong, Zheng Yapeng, Yang Tao, Hou Xinmei
Beijing Advanced Innovation Center for Materials Genome Engineering, Collaborative Innovation Center of Steel Technology, University of Science and Technology Beijing, Beijing 100083, China.
Fundam Res. 2021 Dec 11;2(1):114-122. doi: 10.1016/j.fmre.2021.10.010. eCollection 2022 Jan.
Sn doping is usually adopted to prepare TiAlC in mass production because it can reduce the synthesis temperature while increasing the phase purity. However, excessive Sn doping usually deteriorates the oxidation resistance of TiAlC. Therefore, an appropriate Sn doping concentration is a vital issue. In this work, the effect of Sn doping concentration on the oxidation behavior of TiAlC was systematically investigated by combining theoretical calculations and experimental methods. Density function theory calculations suggest that the oxygen adsorption mechanisms for the (001) surface of TiAlC with and without Sn doping are similar, and Ti-O bonds are always preferentially formed. The molecular dynamics simulation further indicates that Al atoms have a faster diffusion rate during the oxidation process. Therefore, a continuous AlO layer can form rapidly at high temperature. Nevertheless, when the Sn doping concentration exceeds 10 mol%, the continuity of the AlO layer is destroyed, thereby impairing the oxidation resistance of TiAlC. Furthermore, oxidation experiments verify the above results. The oxidation mechanisms of TiAlC with different Sn doping concentrations are also proposed.
在大规模生产中通常采用Sn掺杂来制备TiAlC，因为它可以降低合成温度，同时提高相纯度。然而，过量的Sn掺杂通常会降低TiAlC的抗氧化性。因此，合适的Sn掺杂浓度是一个至关重要的问题。在这项工作中，通过结合理论计算和实验方法，系统地研究了Sn掺杂浓度对TiAlC氧化行为的影响。密度泛函理论计算表明，有Sn掺杂和无Sn掺杂的TiAlC的(001)表面的氧吸附机制相似，并且总是优先形成Ti-O键。分子动力学模拟进一步表明，Al原子在氧化过程中的扩散速率更快。因此，在高温下可以迅速形成连续的AlO层。然而，当Sn掺杂浓度超过10 mol%时，AlO层的连续性被破坏，从而损害了TiAlC的抗氧化性。此外，氧化实验验证了上述结果。还提出了不同Sn掺杂浓度的TiAlC的氧化机制。
