Effects of elements W and C on microstructure and wear property of γ-TiAl surface alloying layer

Abstract

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.

Keywords:

• Double glow plasma surface alloying technique
• TiAl based alloy
• Wear resistance
• H/E and H³/E² ratios

Acknowledgements

This project was supported by National Natural Science Foundation of China (Grant No. 51175247) and the Fundamental Research Funds for the Central Universities (Grant No. NZ2013307).