Review of micro-scale and atomic-scale corrosion mechanisms of second phases in aluminum alloys

Element clustering and structural features of liquid lead-bismuth eutectic (LBE) alloy have been investigated up to 720 °C by means of high temperature X-ray diffraction (HT-XRD), X-ray Photoemission Spectroscopy (XPS) and Scanning Photoemission Microscopy (SPEM) at the Elettra synchrotron in Trieste. The short-range order in liquid metal after melting corresponds to the cuboctahedral atomic arrangement and progressively evolves towards the icosahedral one as temperature increases. Such process, that involve a negative expansion of the alloy, is mainly connected to the reduction of atom distance in Pb–Pb pairs which takes place from 350 °C to 520 °C. On an atomic scale, it is observed a change of the relative number of Bi–Bi, Pb–Pb, and Pb–Bi pairs. The Pb–Bi pairs are detected only at a temperature above ~350 °C, and its fraction progressively increases, giving rise to a more homogeneous distribution of the elements. SPEM results showed evidence that the process of chemical homogenization on an atomic scale is preceded and accompanied by homogenization on micro-scale. Clusters rich of Bi and Pb, which are observed after melting, progressively dissolve as temperature increases: Only a few residuals remain at 350 °C, and no more clusters are detected a 520 °C.

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Mechanics of nanoscale metallic multilayers: From atomic-scale to micro-scale

Scripta Materialia ◽

10.1016/j.scriptamat.2008.11.035 ◽

2009 ◽

Vol 60 (12) ◽

pp. 1067-1072 ◽

Cited By ~ 64

Author(s):

J. Wang ◽

R.G. Hoagland ◽

A. Misra

Keyword(s):

Atomic Scale ◽

Metallic Multilayers ◽

Micro Scale ◽

Nanoscale Metallic Multilayers

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Influence on the Quality of Secondary Aluminum Alloy Casts by Mn Addition

Quality Production Improvement - QPI ◽

10.2478/cqpi-2019-0043 ◽

2019 ◽

Vol 1 (1) ◽

pp. 319-325

Author(s):

Lenka Kuchariková ◽

Eva Tillová ◽

Magdalena Mazur ◽

Adrián Herčko

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Aluminum Alloys ◽

Automotive Industry ◽

Intermetallic Phases ◽

Secondary Aluminum ◽

Cast Alloys ◽

Second Phases ◽

Size And Morphology

Abstract The quality of aluminum casts is necessary in order to reach sufficient properties required for application. The decreasing in the properties of aluminum cast mainly related with microstructure, especially with size and morphology of second phases. One of such second phases in aluminum alloys are the β-phases. These phases are unwonted mainly because of the decreasing of mechanical properties. The contribution is deal with influence of addition of Mn to affecting the formation of β-phases in the AlSi7Mg0.3 and AlSi7Mg0.6 cast alloys. These materials are used for application especially automotive industry. The results shows, that addition of Mn is not sufficient for affecting of formation of the Fe-rich phases in AlSi7Mg0.6 cat alloys, but in the AlSi7Mg0.3 this addition lead to changes in formation of Fe-rich intermetallic phases.

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Interaction between sulfate-reducing bacteria and aluminum alloys—Corrosion mechanisms of 5052 and Al-Zn-In-Cd aluminum alloys

Journal of Material Science and Technology ◽

10.1016/j.jmst.2019.07.009 ◽

2020 ◽

Vol 36 ◽

pp. 55-64 ◽

Cited By ~ 2

Author(s):

Fang Guan ◽

Jizhou Duan ◽

Xiaofan Zhai ◽

Nan Wang ◽

Jie Zhang ◽

...

Keyword(s):

Aluminum Alloys ◽

Sulfate Reducing Bacteria ◽

Sulfate Reducing ◽

Corrosion Mechanisms ◽

Reducing Bacteria

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Layered Double Hydroxide Protective Films Developed on Aluminum and Aluminum Alloys: Synthetic Methods and Anti-Corrosion Mechanisms

Coatings ◽

10.3390/coatings10040428 ◽

2020 ◽

Vol 10 (4) ◽

pp. 428 ◽

Cited By ~ 5

Author(s):

Muhammad Ahsan Iqbal ◽

Luyi Sun ◽

Allyson T. Barrett ◽

Michele Fedel

Keyword(s):

Aluminum Alloys ◽

Synthetic Methods ◽

Self Healing ◽

Structural Variations ◽

Protection Mechanism ◽

Wide Range ◽

Protective Films ◽

Corrosion Mechanisms ◽

Double Hydroxide ◽

Double Hydroxides

This work reviews the characteristics of layered double hydroxides (LDHs) in the context of protective thin films to enhance the corrosion resistance properties of aluminum alloys. A discussion is made in detail about the LDH protection mechanism and the effect of synthesis approaches on LDH structural variations and the corresponding anti-corrosion behavior. LDHs anion-exchange behavior to host inorganic/organic anions makes them a potential material to investigate for anti-corrosion film. This unique advantage and the availability of a wide range of metal oxide-based layers, interlayer anions, and self-healing properties make LDH family an attractive choice for the development of compact LDHs based smart coating systems.

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Atomic-Scale Friction Measurements Using Friction Force Microscopy: Part II—Application to Magnetic Media

Journal of Tribology ◽

10.1115/1.2927241 ◽

1994 ◽

Vol 116 (2) ◽

pp. 389-396 ◽

Cited By ~ 102

Author(s):

Bharat Bhushan ◽

Ju-Ai Ruan

Keyword(s):

Surface Roughness ◽

Friction Force ◽

Coefficient Of Friction ◽

Natural Diamond ◽

Local Variation ◽

Atomic Scale ◽

Poor Correlation ◽

Magnetic Media ◽

Micro Scale ◽

Friction Measurements

Atomic Force/Friction Force Microscopes (AFM/FFM) were used to study tribological properties of metal-particle tapes with two roughnesses, Co-γFe2O3 tapes (unwiped and wiped), and unlubricated and lubricated thin-film magnetic rigid disks (as-polished and standard textured). Nanoindentation studies showed that the hardness of the tapes through the magnetic coating is not uniform. These results are consistent with the fact that the tape surface is a composite and is not homogeneous. Nanoscratch experiments performed on magnetic tapes using silicon nitride tips revealed that deformation and displacement of tape surface material occurred after one pass under light loads (~ 100 nN). A comparison between friction force profiles and the corresponding surface roughness profiles of all samples tested shows a poor correlation between localized values of friction and surface roughness. Detailed studies of friction and surface profiles demonstrate an excellent correlation between localized variation of the slope of the surface roughness along the sliding direction and the localized variation of friction. Micro-scale friction in magnetic media and natural diamond appears to be due to adhesive and ratchet (roughness) mechanisms. Directionality in the local variation of micro-scale friction data was observed as the samples were scanned in either direction, resulting from the scanning direction and the anisotropy in the surface topography. Micro-scale coefficient of friction is generally found to be smaller than the macro coefficient of friction as there may be less ploughing contribution in micro-scale measurements.

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