Abstract
The purpose of this study is to investigate the effect of post-annealing and substrate bias on the mechanical properties and corrosion behavior of Zr-Cu-Ag-Al metallic films. The metallic films were deposited on p-type (100) Si wafer and 304 stainless steel substrates using unbalanced magnetron sputtering. The Zr-Cu-Ag-Al metallic glass (MG) films were deposited at room temperature. The compositions of the MG thin films were uniformly distributed through thickness; however, Ag composition in the films was significantly lower than that in the sputtering target, which may be attributed to re-sputtering effect. The MG films were annealed in vacuum at 250□C for 1 hour, by which the metallic films were crystallized and the crystalline phases were characterized by X-ray diffraction, where the major phases included ZrO2, CuZrO3, Cu10Zr7, AlCu2Zr, and Al3Zr5. The property changes were obviously due to crystallization by post-annealing. For the mechanical properties, the hardness of the crystalline films was higher than the as-deposited counterparts. In addition, the packing density of the MG films increased and electric resistivity decreased after annealing. The residual stress of the as-deposited films was compressive and decreased with thickness; after annealing the stress changed to tensile state for most of the samples. The potentiodynamic polarization scanning was performed in 1N H2SO4+ 0.05 M KSCN solutions to evaluate the corrosion resistance of the metallic film coated 304 stainless steel. The results showed that the corrosion resistance of MG coated-304 stainless steel, in both amorphous and crystalline phases, was significantly improved. The corrosion resistance of the crystalline coatings substantially increased, which was mainly contributed from the surface oxide layer. The salt spray test results of the MG films were not satisfactory. The deterioration of the MG coatings, both amorphous and crystalline structure, in the salt spray test is mainly due to the attack of chloride ions and the formation of ZrClO.43 and CrCl3 compounds, which leads to the spallation of the coatings.