TiAlNb9合金表面Cr-Al-Y共渗层组织结构及高温氧化性能

Microstructure and High-Temperature Oxidation Resistance of Cr-Al-Y Co-deposition Coating on TiAlNb9 Alloy Surface

摘要:

为提高TiAlNb9合金的抗高温氧化性能，采用包埋渗的方法，在合金表面制备了Cr-Al-Y共渗层，通过扫描电子显微镜、能谱仪和X射线衍射仪分析了渗层的组织结构，对比研究了基体和渗层在1273 K下的高温氧化性能。结果表明：Cr-Al-Y共渗层约30 μm厚，结构致密，膜基结合较好，由外到内依次为由TiCr₂、TiCr、Ti₄Cr及(Ti, Nb)Cr₄相组成的外层，Ti₂Al内层及富Nb的γ-TiAl互扩散层。TiAlNb9基体在1273 K下生成TiO₂与Al₂O₃组成的氧化层，由于TiO₂形成的氧化膜结构疏松多孔，无法有效隔绝O元素的内扩散，致使基体不断受到氧化破坏。Cr-Al-Y渗层在氧化时会形成致密的Cr₂O₃和Al₂O₃氧化层，有效阻止了O元素的内扩散，显著提高了基体合金的抗高温氧化性能。

Abstract:

To improve the high-temperature oxidation resistance of TiAlNb9 alloy, a Cr-Al-Y co-deposition coating was prepared on the alloy surface by the pack cementation method. The microstructure of the coating was analyzed by scanning electron microscope, energy dispersive spectrometer, and X-ray diffractometer, and the high-temperature oxidation properties of the substrate and coating at 1273 K were compared and studied. The results show that the Cr-Al-Y coating is about 30 μm in thickness, and it has a dense structure and good film-substrate bonding. The coating includes an outer layer composed of TiCr₂, TiCr, Ti₄Cr, and (Ti,Nb)Cr₄ phases as well as an inner layer composed of Ti₂Al, and Nb-rich γ-TiAl interdiffusion zone. The TiAlNb9 substrate forms an oxide layer composed of TiO₂ and Al₂O₃ at 1273 K. Due to its loose and porous structure, TiO₂ oxide film cannot effectively isolate the internal diffusion of element O, resulting in continuous oxidation damage to the substrate. The Cr-Al-Y co-deposition coating forms a dense Cr₂O₃ and Al₂O₃ oxide layer during oxidation, effectively preventing the internal diffusion of element O and significantly improving the high-temperature oxidation resistance of the substrate alloy.