Oxidation Protection of γ-TiAl Alloys by Intermetallic Ti-Al-Cr-Zr Coatings
Oxidation Protection of γ-TiAl Alloys by Intermetallic Ti-Al-Cr-Zr Coatings
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Ti-Al-Cr-Zr金属间化合物涂层对γ-TiAl合金的氧化防护
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
P. Hovsepian
中科院分区：
文献类型：
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作者：
R. Braun;K. Kelm;A. Ehiasarian;P. Hovsepian
研究了Ti-49Al-34Cr-4Zr金属间层包覆的γ-TiAl试样在1000℃实验室空气循环条件下的氧化行为。采用高功率脉冲磁控溅射和不平衡磁控溅射相结合的方法制备了11 μm厚的涂层。镀层具有致密的层状结构，与基体具有良好的附着力。Ti-Al-Cr-Zr涂层具有较高的抗氧化性，在1000°C下超过1000个循环，停留时间为1小时，可以形成薄的连续氧化铝层。在高温下，沉积状态下的非晶态涂层呈现出不同的多型Ti(Cr,Al) 2 Laves相，Ti可能部分被Zr和Nb取代。由于氧化铝的形成和相互扩散，涂层中铝和铬的含量减少，钛的含量增加。在1000°C下循环1000次后，涂层由六方C14 Laves相的外层和结构尚未确定的可能正交相的内层组成。在这两层中均发现了富含Zr和Y的孔隙和细小沉淀。
The oxidation behavior of γ-TiAl specimens coated with an intermetallic Ti-49Al-34Cr-4Zr layer was investigated at 1000°C under cyclic conditions in laboratory air. The 11 μm thick coating was produced using a combined technique of high power impulse magnetron sputtering and unbalanced magnetron sputtering. The as-deposited coating exhibited a dense layered structure and excellent adhesion to the substrate. The Ti-Al-Cr-Zr coating possessed high oxidation resistance associated with the formation of a thin continuous alumina scale for exposure time periods exceeding 1000 cycles of 1 h dwell time at 1000°C. During the high temperature exposure, the coating being amorphous in the as-deposited condition became crystalline exhibiting different polytypes of Ti(Cr,Al) 2 Laves phases with Ti probably partially substituted by Zr and Nb. Due to alumina formation and interdiffusion the coating was depleted in aluminum and chromium as well as enriched in titanium. After 1000 cycles at 1000°C, the coating consisted of an outer layer of the hexagonal C14 Laves phase and an inner layer of a probably orthorhombic phase whose structure was not yet determined. In both layers, pores and fine precipitates rich in Zr and Y were found.