Scanning Kelvin Probe Force Microscopy and Density Functional Theory Studies on the Surface Potential of the Intermetallics in AA7075-T6 Alloys

Journal Article · Mon Jul 15 04:00:00 EDT 2019 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/S11665-019-04160-6· OSTI ID:22970667

Li, Ni; Dong, Chaofang; Wei, Xin; Man, Chen; Yao, Jizheng; Cao, Jiangli; Li, Xiaogang ^[1]

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1. 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, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 7 Vol. 28; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTAL LATTICES
DENSITY FUNCTIONAL METHOD
INTERMETALLIC COMPOUNDS
MAGNESIUM SILICIDES
MATRICES
MICROSCOPY
PROBES
SURFACE ENERGY
SURFACE POTENTIAL
WORK FUNCTIONS