Characteristics of surface layers on Ti6Al4V alloy borided with CeO2 near the transition temperature

In the present work, to investigate the effects of rare earth element on the microstructure, hardness, wear and corrosion properties of the surface ceramic layers on the borided Ti6Al4V alloy, the pack boriding experiments were performed by adding CeO2 to the boriding agent. The characteristics of boride layers were investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM), electron probe microanalysis (EPMA), wear test, electrochemical test, etc. The results show that the boride layers are composed of a continuous TiB2 top-layer and TiB whisker sublayer. The growth of TiB whisker can be improved by adding CeO2. The surface hardness of TiB2 layer is almost 10 times higher than that of the as-received Ti6Al4V alloy. In addition, the addition of CeO2 can significantly improve the friction coefficient, and the wear mechanism of the borided sample is the abrasive wear. Furthermore, Ti6Al4V alloy borided with CeO2 has a better corrosion resistance than that without CeO2.