不同涂层对纤维增强TiAl基复合材料界面及其性能的影响

On interface and Bending Properties of TiAl Intermetallic Composites with Differently Coated Ti -Fibers

研究了Ａｌ２Ｏ３、Ｙ２Ｏ３及Ｙ２Ｏ３－Ｃｒ涂层对Ｔｉ纤维增强ＴｉＡｌ基复合材料界面和性能的影响。试验结果表明，用ＰＶＤ法给纤维表面涂覆Ａｌ２Ｏ３或Ｙ２Ｏ３的Ｔｉ纤维增强ＴｉＡｌ基复合材料，不仅使γ－ＴｉＡｌ的弯曲强度分别提高２８％和２５％，而且使界面反应层厚度由３０μｍ分别减少到２０μｍ和１４μｍ，即ＹＬＯ３较Ａｌ２Ｏ３有较高的稳定性和较好的扩散障作用。涂覆复合软质涂层Ｙ２Ｏ３－Ｃｒ的Ｔｉ纤维复合材料，其界面除有Ｔｉ３Ａｌ、Ｔｉ２Ａｌ外，有韧性相β及Ｔｉ２Ｃｕ产生，界面结合完整，其材料的弯曲强度达到７０９ＭＰａ，较γ－ＴｉＡｌ提高５８％，较涂覆Ｙ２Ｏ３的Ｔｉ纤维增强ＴｉＡｌ基复合材料提高２６％，而且弯曲挠度有所改善，显示出好的强韧化作用。

In the open literature, coating fiber reinforced intermetallic composite is seldom reported. In this paper we use three -point bending test to study the bending properties of γ-TiAl intermetallic compound matrix composites reinforced with ductile Ti -fibers that are coated in three ways:(1) single Al2O3,(2) single Y2O3,(3)composite soft Y2O3 -Cr. Research results show that by adding single Al2O3 or Y2O3 coating on the surface of Ti -fiber, the room temperature bending strengths can be increased from 449 MPa(unreinforced) to respectively 573 MPa (Al2O3) and to 562 MPa (Y2O3). Thicknesses of the interfacial reaction layers of the fiber -matrix are decreased from 30 μm (uncoated)to respectively 20 μm(Al2O3)and to 14 μm(Y2O3 ). It can be seen that Y2O3 is the more stable barrier against diffusion.Important findings are that: ① Y2O3 -Cr composite soft coating(csc) Ti -fibers make the interface bonding of Ti/TiAl composites intact; ②there is reaction production of brittle phases (α2-Ti3Al and Ti2Al)and tough phases (Ti2Cu and β-Ti) in the interface;③ microstructure of γ-TiAl near the interface tends to transform into thin laminas.The room temperature bending strength of the Y2O3 -Cr csc composites has been further increased to 709 MPa, higher than that for composites coated with single Y2O3,and room temperature bending deflection remains about the same.