摘要
研究了添加不同含量稀土氧化物La2O3对TiAl合金预涂NiCr-Cr3C2混合粉末激光熔覆复合材料涂层组织、耐磨性及抗氧化性能的影响,分析了La2O3的作用机理。结果表明,激光熔覆涂层的组织主要由大量较规则初生块状Cr7C3,细小粒状或树枝状TiC以及γ/Cr7C3共晶组成;随着La2O3的加入,初生相明显细化、球化,共晶组织数量增多,适当的(质量分数4%)La2O3的添加能提高涂层的硬度、韧性和耐磨性,并改善其抗氧化性能。这主要是由于稀土元素对显微组织的细化和涂层的净化作用,显微组织的细化提高了涂层的强度、韧性和硬度,而涂层的净化可以降低其夹杂物的含量,进而提高氧化膜的致密性和附着性,这些都有利于提高其耐磨性和抗氧化性。
The effects of La2O3 addition on microstructure, wear and oxidation properties of laser clad composite coatings on TiAl intermetallic alloy substrates with NiCr-Cr3C2 precursor mixed powders have been investigated. The corresponding wear and oxidation mechanisms are also discussed based on the experimental results. The results show that no evident new crystallographic phases are formed except a rapidly solidified microstructure consisting of the primary hard Cr7C3 and TiC carbides and the γ/Cr7C3 eutectics distributed in the tough γ nickel solid solution matrix. The additions of rare earth oxide La2O3 can refine and purify the microstructure of the coatings, relatively decrease the volume fraction of primary blocky Cr7C3 to Cr7C3/γ eutectics and increase the microhardness of the coatings. The refinement of the microstructure is beneficial to improving the microhardness, strength and toughness of the coatings, the purification and compactness of the coatings is in favor of the wear and oxidation resistance. The composite coating with 4 wt.-% La2O3 addition can result the best enhancement of wear and oxidation resistance. However, too less or excessive addition amount of La2O3 have no better influence on wear and oxidation properties of the composite coatings.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2005年第7期1011-1016,共6页
Chinese Journal of Lasers
关键词
激光技术
TIAL合金
La2O3激光熔覆
显微组织
耐磨性
抗氧化性
Aluminum alloys
Cladding (coating)
Composite materials
Composition effects
Intermetallics
Lanthanum compounds
Microhardness
Microstructure
Oxidation resistance
Titanium alloys
Volume fraction
Wear resistance
