Si对TiAl合金高温抗氧化性能的影响

利用X射线衍射、扫描电镜、能谱仪等手段研究了TiAl-Si(原子数分数为0~20%)合金在1?173?K大气中24?h的恒温氧化.结果表明:Si元素可以有效地提高TiAl合金的高温抗氧化性能;随着Si含量的增加,氧化膜厚度依次减薄,TiO₂的含量逐渐减少,Al₂O3的含量逐渐增加,添加到10%左右时就有连续致密的Al₂O₃保护膜形成;Si在0~20%的添加过程中并没发现Si的氧化物生成.分析表明:Si对抗氧化性能的贡献可归结于Si与Ti有很好的亲和力,可以有效地降低Ti离子的活度、阻碍Ti离子的向外扩散, 相对来说增强了Al离子的活度,促进连续致密的Al₂O₃保护膜生成.

Effects of Si on high temperature oxidation resistance of TiAl alloy

The isothermal oxidation of TiAl-Si(atom percent is 0~20%) alloys at 1?173?K, 24 hours on atmosphere were studied by X-ray diffraction,scanning electron microscopy and energy dispersive spectrum. The results reveals that the addition of Si improves the oxidation resistance of TiAl alloys. With increasing of Si content, the thickness of oxidation films and TiO₂ content are decreasing, and the content of Al₂O₃ is increasing. when the addition of Si reaches 10%, the continuous and compacted oxide film of Al₂O₃ is preferentially formed on the surface of TiAl alloy. During the addition of Si content from 0 to 20%, no any form of oxide of Si appears. The main reason of the improvement of oxidation resistance is attribute to Si combination with Ti, which results in the decrease of the activity of Ti, baffles Ti-ions outward diffusion, therefore relatively enhances the activity of Al, and the compacted oxide film of Al₂O₃ is preferentially formed on the surface of TiAl alloy.