TEM Investigation on the Surface Nanostructured Layer of CP-Titanium

A new method of preparing TEM cross-sectional specimens from surface nanocrystallized (SNC) samples was presented; by this method, commercially pure titanium (CP-Ti) with high-energy-shot-peened (HESP) treatment was observed and analyzed using TEM. The observation results show that about 10 mu m thick nanostructured layer was achieved on the surface of CP-Ti after HESP treatment with appropriate parameters using modified shot peening equipment. The grain size changes gradually from the top surface to the inner so that no evident interface exists between the nano-layer and the substrate. The grains in the top surface layer are randomly orientated and equiaxed nanocrystallites, whose size is about 50 nm. The above-mentioned results indicate that the easily-happened bending of the SNCed specimen due to the residual stress is eliminated through the specimen preparation procedure, and proper specimens that are fit for TEM observation obtained.