Effects of ultrasonic nanocrystal surface modification on the thermal oxidation behavior of Ti6Al4V

The effects of Ultrasonic Nanocrystal Surface Modification (UNSM) on the thermal oxidation (TO) behavior of Ti6Al4V alloy has been investigated. The thermal oxidation was carried out at 500, 600 and 700 °C. The microstructure after UNSM and TO was characterized using scanning electron microscopy with energy dispersive spectroscopy. And phase identification was performed using X-ray diffraction. At 500 and 600 °C, the reaction capability are enhanced and the oxidation layer thickness is increased in the UNSM-treated Ti6Al4V alloy. This is attributed to nanoscale grain boundaries created by UNSM that serve as efficient diffusivity paths for interstitial gaseous atoms. When the TO temperature rises to 700 °C, due to dislocation elimination and grain coarsening induced by the high temperature, the oxidation layer thickness of the Ti6Al4V specimens show no significant difference.