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Ti–CrNi alloy coatings with 20, 40, 60 and 80 at-%Ni were prepared on Ti6Al4V alloy surface by double glow plasma surface alloying technique. The cyclic oxidation behaviour of the coatings was investigated at 750, 850 and 950°C. The results show that each coating has a complete structure of settled layer, mutual diffusion layer and sputtering affected zone. When the Ni content was 40 at-%, the Ti–CrNi alloy coating showed the best cyclic oxidation resistance. The oxide scale with ‘Cr2O3film+NiO film’ structure showed the best resistance to peeling. [ABSTRACT FROM AUTHOR]

To solve the poor tribological property of the γ-TiAl alloy, the duplex treatment of plasma carburisation on plasma alloying γ-TiAl with tungsten was conducted by double glow plasma surface alloying technique. The results indicated the alloying layer consisted of TiC and W2C phase, metallurgically adhered to the substrate. In terms of the H/E and H3/E2 ratios, the duplex treated specimen was nearly three times larger than the untreated specimen. The wear property of the specimens was tested on a pin-on-disk tribometer by rubbing against Si3N4 ceramic ball. The wear rate of the duplex-treated specimens is 1·056×10−4 mm3 N−1 m−1, which is only 25·9% of that of the untreated specimens. The relationship between alloying layer mechanical property and wear resistance indicates that the carbide phase formed within the alloying layer contributes to the improvement of the wear performance. [ABSTRACT FROM AUTHOR]

Zirconium (Zr) alloying layer was formed in the TC11 surface by using the double glow plasma surface alloying technique. The microstructure, surface hardness and oxidation resistance of the alloying layer were investigated by X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectrometry, respectively. The results showed that the alloying layer consisted of a compact and homogeneous Ti-Zr mutual diffusion layer, and the surface alloying elements all displayed gradient distributions. The zirconium alloying layer enhanced the surface hardness by solution strengthening. The improvement of TC11 oxidation resistance was due to the formation of compact and uniform oxide scales, which was consisted of ZrO2 as the major phase and TiO2 as the minor phase. [ABSTRACT FROM AUTHOR]