TiAl合金表面Si-Al-Y共渗层的组织与摩擦磨损性能

Microstructures and Wear Resistance of Si-Al-Y Codeposition Coatings on TiAl Alloy

通过1050℃下Si-Al-Y2O3扩散共渗4 h的方法在TiAl合金表面制备了Y改性的Si-Al共渗层,采用SEM、EDS和XRD分析共渗层的结构及相组成,并对TiAl合金基体及共渗层的常温(20℃)及高温(600℃)耐磨性进行研究。结果表明:1050℃下共渗4 h所制备的Si-Al-Y共渗层具有多层复合结构,由外向内依次为TiSi2外层,(Ti,X)5Si4(X表示元素Nb和Cr)及(Ti,X)5Si3中间层,TiAl2和γ-TiAl内层及富Al的过渡层组成;在常温和600℃高温条件下,Si-Al-Y共渗层的耐磨性均明显优于TiAl合金基体,并且Si-Al-Y共渗层具有良好的耐高温磨损性能,在实验温度条件下其磨损机理无明显变化,均为剥层磨损和磨粒磨损;TiAl合金基体在常温下的磨损机理为犁削磨损和磨粒磨损,在600℃高温下的磨损机理为犁削磨损、氧化磨损和磨粒磨损。

Si-A1-Y co-deposition coatings on TiA1 alloy were prepared by pack cementation processes at 1050 ℃ for 4 h.Scanning electron microscope （SEM）,energy dispersive X-ray spectrometer （EDS） and X-ray diffractmeter （XRD） were employed to investigate the surface morphologies,microstructures and phase constitutions of the coatings.Friction-wear tests of the TiA1 alloy substrate and the coatings were conducted in air at normal （20 ℃） and high （600 ℃） temperature.The results show that the coating prepared by co-deposited Si-A1-Y has a multiple layer structure：an outer layer composed of TiSi2,a middle layer composed of （Ti,X）5Si4 （X represents Nb and Cr elements） and （Ti,X）5Si3,an inner layer composed of TiAl2 and γ-TiAl,and a A1 rich-interdiffusion zone.The wear resistance of Si-Al-Y coating is obviously better than that of TiA1 alloy at normal and high temperature,and it has good wear resistance performance at high temperature.The wear mechanism of the coating has no significant changes at experimental temperature that is delamination abrasion and grain-abrasion.The wear mechanisms of TiAl alloy are grinding abrasion and grain-abrasion at normal temperature,and are grinding abrasion and grain-abrasion and oxidation abrasion at 600 ℃.