Effect Of Annealing Treatment On Electronic Work Function And The Related Properties Of Bulk Metallic Glass

Bulk metallic glasses (BMGs) with a unique atomic structure have many excellent unique properties, such as superior strength, high wear resistance, excellent corrosion resistance and fatigue resistance, which have become one of the hotspot in material researches. Numerous studies show that the Zr-base BMGs have the strong glass forming ability (GFA) and large supercooled liquid regions (SLR), they can be more easy to prepare by simple equipment, and show very excellent corrosion resistance. Compared with Zr-base BMGs, the Cu-base BMGs have higher compression strength, tensile strength and good plastic, As well as lower preparation cost in engineering application. But the brittleness and the difficult to preparation of amorphous alloys limit their wide application seriously.In this work, the electronic work function, mechanical properties and corrosion resistance were studied based on the scanning Kelvin probe (SKP) techniques. By measuring the variety of the EWF, mechanical properties and corrosion resistance of the BMGs,we analyzed deformation behaviores , surface corrosion behaviores and microstructure of the research objectives on the atomic scale. Therefore, we provided a more reasonable method for the further guidance of BMGs design. The main contents of our work are listed as follows:(1) We prepared Zr₆₅Al_7.5Cu_17.5Ni₁₀ ribbon amorphous alloy and Cu46Zr47Al7 BMG. In order to understand the effects of annealing treatment for the mechanical properties, corrosion resistance and EWF, the amorphous alloy were annealed at different temperatures, which followed by the thermal analysis and crystalline structure of the samples characterized by the X-ray diffraction (XRD), the differential scanning calorimetry (DSC), and the scanning electron microscope (SEM).(2) The effects of crystallization on the electron work function and corrosion resistance of Zr₆₅Al_7.5Cu_17.5Ni₁₀ amorphous alloys in 1 mol/L HCl, 3.5% NaCl and 0.5mol/L H2SO4 solution were studied by using scanning Kelvin probing and electrochemical technique. The present work showed that the single phase of amorphous alloy exhibited the better corrosion resistance and higher EWF than partially crystallined alloys and full crystallization alloy with the same alloy composition; and a close relationship between corrosion resistance and EWF, indicating that the EWF could be a sensitive parameter for characterizing and investigating the corrosion behavior of amorphous alloy at the electronic level.(3) The mechanical properties and electronic work function of Cu46Zr47Al7 bulk metallic glass were measured by using compressive measurement and the scanning Kelvin probe technology. It's found that the Cu-base amorphous sample has the higher EWF, yet the precipitate of the amorphous alloy made the mechanical properties and EWF reduced. For the annealed samples, with the increase of the annealing temperature, the interfaces between the crystalline phase and the amorphous matrix and the defects between the grain boundaries reduced. Therefore, more energy should be needed when the electron escape from the surface. In the meantime,the compressive deformation and the fracture behaviors changed from ductility to brittleness with the increase of the annealing temperature for the Cu46Zr47Al7 bulk metallic glass composites.