TiAl合金激光熔覆金属硅化物复合材料涂层组织研究

Study on the Microstructure of Laser Clad Metallic Silicide Composite Coatings on TiAl Intermetallic Alloy

利用预涂NiCr-Si复合粉末对TiAl合金进行激光熔覆处理,分析了涂层的显微组织及其形成机理,并讨论了显微组织与预涂合金粉末成分的关系。结果表明:涂层的显微组织由初生块状Ti5Si3相及点状-γNiCrAl/TiSi共晶组织组成,随着预涂合金粉末中Si含量的增加,涂层中初生Ti5Si3块状相的体积分数增大,显微硬度提高,涂层与基体之间为良好的冶金结合。

γ-NiCrAl/Ti5Si3/TiSi composite coatings were fabricated on γ-TiAl intermetallic alloy by laser cladding pre-placed with NiCr-Si mixed powders. The microstructure of the laser clad metallic silicide composite coatings are characterized as function of constitution of the mixed precursor powders and their microstructural evolution process are discussed. The results show that microstructure of the laser clad composite coatings consists of primary blocky Ti5Si3 and dot-like γ/TiSi eutectics and is metallurgically bonded to the TiAl substrate. The volume fraction of the primary Ti5Si3 reinforced blocks and the microhardness of the laser clad composite coatings increases with the increasing of Si content in the mixed powder pre-coatings.