Scanning Kelvin Probe Force Microscopy and Density Functional Theory Studies on the Surface Potential of the Intermetallics in AA7075-T6 Alloys
- University of Science and Technology Beijing, Corrosion and Protection Center, Key Laboratory for Corrosion and Protection (MOE) (China)
The surface potentials of Mg{sub 2}Si and Al{sub 7}Cu{sub 2}Fe intermetallic particles in AA7075-T6 alloys were investigated by scanning Kelvin probe force microscopy (SKPFM) technique. The experimental surface potentials of Mg{sub 2}Si and Al{sub 7}Cu{sub 2}Fe intermetallic particles relative to Al matrix were ranging from − 368 to − 265 mV and 480–500 mV, respectively. A theoretical method for assessing relative nobility of intermetallics in Al alloys was discussed through first principle calculation. The work functions and surface energies of Mg{sub 2}Si and Al{sub 7}Cu{sub 2}Fe surfaces were calculated by using density functional theory (DFT) method. The results showed that work functions and surface energies of Mg{sub 2}Si and Al{sub 7}Cu{sub 2}Fe intermetallics were influenced by the orientations of crystal face and terminal types. At the oxygen coverage of 1/4 ML and 1 ML, the theoretical surface potential differences between Mg{sub 2}Si intermetallics and Al matrix were increased by 10–560 mV and 0–620 mV, while those between Al{sub 7}Cu{sub 2}Fe intermetallics and Al matrix were increased by 62–360 mV and 102–331 mV. For the adsorption of oxygen atom, theoretical surface potentials of Mg{sub 2}Si and Al{sub 7}Cu{sub 2}Fe intermetallics relative to Al matrix had a close agreement with the experimental surface potentials. It was verified that DFT method was a valuable theoretical approach to assess the relative nobility of different phases in alloys.
- OSTI ID:
- 22970667
- Journal Information:
- Journal of Materials Engineering and Performance, Vol. 28, Issue 7; Conference: 73. World Foundry Congress, Krakow (Poland), 23-27 Sep 2018; Other Information: Copyright (c) 2019 ASM International; Country of input: International Atomic Energy Agency (IAEA); ISSN 1059-9495
- Country of Publication:
- United States
- Language:
- English
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