The oxidation behaviour of a novel Ti with a nanocrystalline (NC) surface layer, made by surface mechanical attrition treatment (SMAT Ti), has been investigated in air at 500∼700 °C. SMAT Ti can react with oxygen and form oxide particles even at 500 °C, while that of coarse-grained Ti (CG Ti) is about 600 °C. Ti shows a different colour at each temperature, which is attributed to the light interference phenomena. The SMAT Ti shows a thicker, denser oxide layer as compared with that of CG Ti. It originates from the numerous grain boundaries and dislocations on the SMAT Ti surface.
The authors acknowledge support from the National Natural Science Foundation of China (Grant No. 51004055), the Natural Science Foundation of Yunnan province, China (Grant No. 2008CD201) and the Cultivate Objects for Technology Innovation Talents of Yunnan Province (Grant No. 2009CI081).