TiAl-Nb基合金高温抗氧化研究进展

TiAl-Nb基合金具有优异的综合性能,在先进飞行器及武器等耐高温部件中有巨大的应用潜力,但其高温抗氧化性能无法满足实际使用需求。综述了TiAl-Nb基合金高温抗氧化防护方面的研究进展,包括TiAl-Nb基合金的多元合金化、表面合金化、抗氧化涂层及其抗氧化机理,通过分析不同氧化防护措施的特性,展望了TiAl-Nb基合金高温抗氧化防护的发展趋势。国内外研究结果显示,通过多元合金化方法改善合金组织,并在氧化过程中促进形成保护性Al_2O_3而抑制形成TiO_2,是提高TiAl-Nb基合金高温抗氧化性能的有效手段。利用表面合金化对合金表面的显微组织和成分进行改善,氧化时促进抗氧化性能优良的Al_2O_3或SiO_2保护膜形成,显著提高了TiAl-Nb基合金的抗氧化性能。但高温下合金化层与基体之间的Al、Si、Ti等元素的互扩散会加剧合金化层的退化,进行表面多元合金化,特别是添加微量活性元素,对促进保护性氧化膜的形成及抑制互扩散有良好效果。通过制备表面抗氧化涂层,在氧化时生成保护性氧化膜,阻碍O的内扩散,能够起到良好的高温抗氧化作用,但需要解决涂层/基体合金的结合力较差和反应扩散等问题,制备复合涂层或扩散阻挡层是解决上述问题的有效途径。

High-temperature Antioxidation of TiAl-Nb Based Alloys

TiAl-Nb based alloys have great application potential in high temperature components of advanced aircrafts and weapons due to excellent overall performance. However, high-temperature oxidation resistance of these alloys could not meet requirements of actual service. Research progress on high-temperature antioxidation protection of TiAl-Nb based alloys was reviewed, covering multi-alloying, surface alloying, oxidation resistant coatings and high-temperature antioxidation mechanisms. Meanwhile, characteristics of different oxidation protection measures were analyzed, and development trend of high-temperature antioxidation protection of TiAl-Nb based alloys were prospected. Domestic and foreign studies showed that multi-alloying was an effective way to promote the high-temperature oxidation resistance of TiAl-Nb based alloys by improving microstructures and/or promoting formation of protective Al2O3 scale while suppressing formation of TiO2 during oxidation. Surface alloying could significantly promote oxidation resistance of TiAl-Nb based alloys by improving microstructures and constituents of alloy surface, and promoting formation of Al2O3 or SiO2 protective films during oxidation. However, inter-diffusion of Al, Si and Ti etc. between alloying layer and the substrates would exacerbate degradation of the alloying layer. Surface multi-alloying especially addition of minor reactive elements had good effects on promoting formation of protective oxide films and suppressing inter-diffusion. Preparing oxidation resistant coatings which formed protective oxide film and suppressed internal diffusion of O during oxidation was also an effective way to achieve excellent high-temperature oxidation resistance of the alloys. However, poor bonding strength and reaction-diffusion between the coatings and substrates should be solved carefully, and preparing composite coatings or diffusion impervious layers is proved to be effective in resolving above problems.