Scanning Kelvin Probe Force Microscopy

Blücher, Daniel Bengtsson; Svensson, Jan‐Erik; Johansson, Lars‐Gunnar; Rohwerder, Michael; Stratmann, M.

doi:10.1149/1.1809590

Cited by 64 publications

(28 citation statements)

References 25 publications

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“…40 Scanning Kelvin Probe Force Microscopy (SKPFM) was used to evaluate the nobility of secondary phases. 5,41 Fig. 4 shows the surface potential maps and profiles of AZ91GC and AZ91RC alloys.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Corrosion Resistance of AZ91 Alloy Produced by Semisolid Metal Processing

Mingo

Arrabal

Mohedano

et al. 2015

J. Electrochem. Soc.

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Rheocast AZ91 magnesium alloy was evaluated in terms of microstructure and corrosion resistance. Rheocasting leads to a globular microstructure of α-Mg spheres separated by an interconnected β-Mg 17 Al 12 (β-phase) network. Findings revealed that early stages of corrosion were located at the center of α-Mg globules and more importantly at α-Mg/β-phase interfaces due to galvanic coupling as predicted from surface potential maps. Electrochemical, hydrogen evolution and weight loss measurements demonstrated the superior corrosion resistance of the rheocast alloy. This was attributed to an improved barrier effect of the β-Mg 17 Al 12 phase and, possibly, to a smaller area fraction of Al-(Mn,Fe) inclusions. For long immersion times, only small attacked areas were observed which corresponded to randomly corroded α-Mg globules.The automotive industry is developing new processing techniques for magnesium alloys which are able to minimize the disadvantages of conventional processing routes such as high porosity, compositional segregation and poor mechanical properties. 1 Semisolid metal (SSM) processing has been shown to be an outstanding manufacturing technique to produce high performance and reliable materials at low cost. 2,3 SSM processing is also able to produce near-net shape components with enhanced corrosion and mechanical properties. 4 The basic feature of SSM processing is the formation of a thixotropic suspension of solid spheres immersed in a liquid matrix. To that end, the material is heated up to the biphasic solid-liquid region under continuous agitation. 2,5,6 The rheological properties of the mixture allow the filling of the molds under laminar flow conditions which facilitates the use of geometrically complex molds. In addition, the porosity of the work piece is considerably reduced since gas entrapment is restricted and the shrinkage during solidification from the biphasic region is lower compared to direct solidification from the liquid state. 7 The resultant material exhibits high dimensional stability, improved surface quality and better mechanical properties derived from the uniform and defect-free globular microstructure obtained during the stirring process. 5 Additionally, the use of SSM processing results in an improvement of the energy efficiency derived from the lower temperatures used during the manufacturing process and a higher yield due to lower oxidation rates of the alloy. 8 The growing need to decrease vehicle weight has situated Mg-Al alloys as excellent candidates for substitution of traditional structural materials due to their low density, good damping capacity, high specific strength, machinability and high thermal conductivity. 9-11 Mg-Al alloys suit perfectly the SSM processing technology since they have a wide solidification range which facilitates holding the mixture in the semisolid state. Additionally, the reduced temperatures and laminar filling used in SSM processing prevent the incorporation of oxides into the mold that are usually formed due to the high reactivity of Mg. 1...

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Section: Resultsmentioning

confidence: 99%

Enhanced Corrosion Resistance of AZ91 Alloy Produced by Semisolid Metal Processing

Mingo

Arrabal

Mohedano

et al. 2015

J. Electrochem. Soc.

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“…In the past decade many KFM studies have also been conducted on a broad range of topics in corrosion science, including research on the corrosion behavior of steel [136][137][138][139][140][141][142][143][144], Al [143], Cu [145][146][147][148], Zn [143,144,[149][150][151][152], alloys based on Al-Mg [153][154][155][156][157][158][159][160][161][162][163][164] and Ti [165], on corrosion protection with rare-earth elements [166] and other inhibitors [167][168][169][170], the effect of conversion coatings [171][172][173][174][175][176], and the effects of heat treatment on material properties [177][178][179]. Yamawaki et al …”

Section: Metalsmentioning

confidence: 99%

Multidimensional electrochemical imaging in materials science

2007

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In the past 20 years the characterization of electroactive surfaces and electrode reactions by scanning probe techniques has advanced significantly, benefiting from instrumental and methodological developments in the field. Electrochemical and electrical analysis instruments are attractive tools for identifying regions of different electrochemical properties and chemical reactivity and contribute to the advancement of molecular electronics. Besides their function as a surface analytical device, they have proved to be unique tools for local synthesis of polymers, metal depots, clusters, etc. This review will focus primarily on progress made by use of scanning electrochemical microscopy (SECM), conductive AFM (C-AFM), electrochemical scanning tunneling microscopy (EC-STM), and surface potential measurements, for example Kelvin probe force microscopy (KFM), for multidimensional imaging of potential-dependent processes on metals and electrified surfaces modified with polymers and self assembled monolayers.

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“…The SKPFM technique allows for the simultaneous mapping of surface topography and the surface potential distribution in air or other gas such as CO 2 environments 6 . An attractive feature of this technique is that it can map the potential locally, with a lateral resolution that can extend down to the nanometer-scale to resolve intermetallic particles in Al alloys.…”

Section: Introductionmentioning

confidence: 99%

Use of Scanning Kelvin Probe Force Microscopy to Investigate the Effects of Surface Preparation on Intermetallic Particles in AA7xxx Aluminum Alloys

Zhang¹,

Yu²,

Kryzman³

et al. 2012

ECS Trans.

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Scanning Kelvin probe force microscopy (SKPFM) was used to quantitatively measure the surface potentials (also referred to as Volta potential) on different intermetallic particles relative to the matrix in AA7xxx aluminum alloys, in combination with scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). Both Cu and Fe-rich intermetallics showed rather high, positive Volta potential differences (~ +400 mV), while Mg/Si-rich one exhibited a negative potential (~ -250 mV) relative to the matrix for the Al alloys investigated. Large variations in the measured Volta potential, which appeared to be independent of particle size, were observed for these Cu and Fe-rich (Al7Cu2Fe) and Mg/Zn rich (Mg2Zn) particles in the custom Al-Zn-Mg-Cu alloy. The effects of different surface preparation on the Volta potentials of Cu/Fe-rich and Mg/Si-rich intermetallic particles were investigated. The results indicate that the influence of surface preparation is complex, but largely depends on the type of intermetallic particles, and whether there is any particle dissolution during the surface preparation.

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Scanning Kelvin Probe Force Microscopy

Cited by 64 publications

References 25 publications

Enhanced Corrosion Resistance of AZ91 Alloy Produced by Semisolid Metal Processing

Enhanced Corrosion Resistance of AZ91 Alloy Produced by Semisolid Metal Processing

Multidimensional electrochemical imaging in materials science

Use of Scanning Kelvin Probe Force Microscopy to Investigate the Effects of Surface Preparation on Intermetallic Particles in AA7xxx Aluminum Alloys

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