Mechanical properties and corrosion behaviour of nanocrystalline surface layer in pure zirconium

摘要

Nanostructured surface layers were formed on pure zirconium using surface mechanical attrition treatment for 0.5-15 min. The nanocrystalline microstructure at the surface of pure zirconium was characterized by means of X-ray diffractometry, transmission electron microscopy (TEM) and high-resolution transmission electron microscory (HRTEM). The effects of SMAT on hardness and corrosion in 1N H2SO4 for zirconium were investigated by Vickers hardness and polarization curves tests respectively. The coarse grains at the top of the surface can be refined into 5-10 nm with different misorientation even for a very short time of 0.5 min. The hardness of the treated surface has been apparently increased. With the increase of the processing time, the hardened layers become thicker. Two remarkable passive regions in polarization curve for the SMATed specimen suggest that the formation of the passive layer on the nanocrystalline zirconium may protect the surface from long-time corrosion in the erodent environment of 1N H2SO4.