Study On The Corrosion Characteristics Of Amorphous Alloy Surface

Because of its unique structure,an amorphous alloy has far more corrosion resistivity than that of crystalline alloy and stainless steel.Corrosion leads to serious harm to the modern society.The world loses about 700 billion US dollars every year due to the corrosion problem.Rust-proof and anti-corrosion remains problems that are hard to be solved.Therefore,investigation of amorphous alloys with good corrosion resistance is of great significance.In this dissertation,Zr_60.5Cu_19.5Al_9.5Ti_5.5Fe₅ bulk metallic glasses were prepared by copper mold casting.The samples were characterized by X-ray diffraction(XRD)and differential scanning calorimetry(DSC).Surface analysis was performed using X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy(SEM).We have analyzed five samples:sample 1(as-prepared amorphous alloy sample);samples 2 and 3 (as-prepared samples underwent immersion in solution of NaCl and HCl,respectively); samples 4 and 5(crystallized samples underwent immersion in solution of NaCl and HCl, respectively).Elemental compositions and their states in the surface layers of the above five samples have been determined by XPS.The mechanism of excellent corrosion resistivity was also discussed.We found that the corrosion resistivity of Zr-based amorphous alloy was far superior to the annealed Zr-based alloys,and the corrosion of HCl solution was more serious than that of NaCl solution.The reasons of the outstanding corrosion resistance performance of Zr-based amorphous alloy are:(1)A metallic glass is a single solid phase and has no dislocation and grain boundaries where corrosion starts.(2)When the surface of the metallic glass suffers from corrosion,it can forms a film of the metal oxides ZrO₂ and TiO₂ which have high chemical stability and can prevent the further corrosion after the spontaneous deactivation.