Research On W And W-C Surface Alloying Process Of The γ-TiAl Based Alloy With Double Glow Plasma Surface Alloying Technique And Properties Of Alloyed Layers

γ-TiAl based alloy has high specific strength, high specific elastic modulus and good high temperature strength and so on. It is considered to be one of the promising high-temperature structural materials, which can be widely used in aeronautics, astronautics, war industry and other industrial sectors. However, the low wear resistance and the poor high-temperature oxidation resistance ofγ-TiAl alloy restrict its practical application, which have become the key issues to be resolved.To solve these problems, The tungstening alloying layer and the W-C composite alloying layer were prepared onγ-TiAl alloy by using the double glow plasma surface alloying technique in this paper. Optical microscopy (OM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM) were used to study the microstructure, chemical composition and phase composition of alloying layer, respectively, the elastic modulus, micro-hardness, tribological properties at both high temperature (500℃) and room temperature and high-temperature oxidation resistance at three temperature (650℃, 750℃and 850℃). In addition, The changes of valence electron structure were calculated with the empirical electron theory of solid and molecule for TiAl-based alloy with different W dissolving into Ti sublattice.Meanwhile, the effect of valence electron structures with different W content on the properties of alloy were discussed.The results show that: In the optimum process parameters, The composition of the surface modification layers distributed gradually from the surface to matrix and formed metallurgical bonding between alloyed layer and substrate. The effective thickness of the plasma tungstened layer was about 30μm and TixW1-x compound was the main alloying phases.while the phases of the W-C composite alloying layer were mainly W2C and TiC. Tungstened layer layer and W-C composite alloying layer have increased the wear resistance of substrate at room temperature and 500℃, especially the increase of W-C composite alloying layer at 500℃is particularly evident. The high-temperature oxidation resistance of two alloying layers at different temperatures showed a greater difference.