Surface nanocrystallization of Ti-6Al-4V alloy: microstructural and mechanical characterization
Journal of Nanoscience and Nanotechnology
In this study, microstructural and mechanical properties of Ti-6Al-4V alloy, before and after the SMA treatment as well as the duplex SMAT/Nitriding process at different treatment conditions, was investigated in order to deepen the knowledge of these properties for biomedical devices. For that purpose, tribological (wear resistance, coefficient of friction) and mechanical (Vickers microhardness) tests were performed. To carry out the microstructural and surface topographical characterization of the samples, the scanning electrom microscopy (SEM) and the 3D-SEM reconstruction from stereoscopic images have been used. By means of profiles deduced from the 3D images, the surface roughness has been calculated. This study allowed to find an interesting SMAT condition which, followed by nitriding at low temperature, can greatly improves tribological properties (wear resistance and coefficient of friction) and the microhardness of Ti-6Al-4V alloy. It was also shown from SEM characterization and the original method of 3D-SEM reconstruction, that SMAT can standardize the machined grooves and consequently reduce the roughness of the samples. On the other hand, we demonstrate that ionic polishing allowed to reveal the grains, the grain boundaries and the twins as well as the surface nanocrystalline layer. Thus, the SMATed layer decreases with the nitriding temperature, whereas the surface grains size increases.
- Pi_2012.pdf (0.6 Mo)