Structure And Properties Of Cr-W Surface Modified Layers On The γ-TiAl Based Alloy Prepared By Double Glow Plasma Surface Alloying Technique

The γ-TiAl based alloy has specialties of low density high specific strength and elastic modulusand good high temperature strength and so on. So it is considered to be one of the promising hightemperature structural materials, and it has great benefit in the development of aeronautics andastronautics, the advanced automotive and steam turbine. However, the low wear resistance and thepoor high-temperature oxidation resistance restrict its application.The401MVA Vickers hardness meter was used to test the micro-hardness and the WS-2006typescratch instrument was used to evaluate the adhesion force between the alloy layer and thesubstrate.The friction and wear performance was analyzed by high temperature friction apparatus atroom temperature and high temperature (500℃).At the same time, the oxidation resistance of alloyedlayer was analyzed by the resistance furnace under different temperatures.The result shows that:(1) Under the optimized process parameters,the ideal Cr-W alloy layer wasobtained on γ-TiAl alloy surface.The component of the alloyed layer was gradient distribution fromthe surface to the substrate,the substrate combined with alloyed layer well,which was metallurgicalcombination.(2) The hardness of Cr-W alloyed layer was648.8HV0.1, which was about two timesthan the substrate.The friction and wear test indicates that Cr-W alloyed layer showed excellentabrasion resistance which improved the wear resistance of γ-TiAl alloy at the room temperature andhigh temperature conditions.(3) High temperature oxidation experiments suggests that, the weightincrement of the oxidation of the alloyed layer were all less than that of γ-TiAl alloy at750℃,850℃and950℃.The surface of alloyed layer forms dense oxidation flim,and improved the resistance ofhigh temperature oxidation of the γ-TiAl alloy.