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High throughput synthesis and corrosion studies on alloys

High throughput synthesis and corrosion studies on alloys
High throughput synthesis and corrosion studies on alloys
A range of Ni-Cr, Ni-W, Al-Mg, and Al-Mg-Zr thin film alloys have been synthesised using a controllable compositional gradient method based on MBE sources allowing the deposition of compositional gradients of a large range of thin film materials. The alloy materials are characterised by X-ray diffraction, including phase identification and crystallite size, and energy dispersive x-ray spectroscopy (EDX). The corrosion resistance of 100 discrete alloy compositions has been measured simultaneously in identical environments using a high-throughput screening protocol based on cyclic voltammetry (CV). The corrosion resistances and potentials are extracted from voltametric data by both the Linear Polarisation Resistance (LPR) and Tafel Extrapolation methods. Results from these are shown to be consistent. In general, the corrosion (polarisation) resistance behaviour is shown to be directly related to the bulk alloy structures or morphologies. In the case of the NiCr alloys, besides the b.c.c ?-Cr (Im3m) phase and its Ni solid solutions, which exhibit the highest polarisation resistances, the ? Cr3Ni2 (P42/mnm) phase exhibits the next best polarisation resistance. The incorporation of W in the Ni-W solid solution at low W compositions resulted in a small reduction in corrosion resistance while a significant increase in the corrosion resistance was observed for alloy compositions greater than 24 %at. W. The best corrosion resistance of Al-Mg alloys was observed for alloy compositions comprise 35%at. Al, which corresponds to the formation of ? Al12Mg17 (i.e. also named ? phase). The incorporation of Zr in the Al-Mg resulted in forming five Al-Zr metastable phases i.e. Al3Zr, Al2Zr, Al3Zr2, Al4Zr5, and Al3Zr5. The Al-Mg-Zr alloys composition contained Al3Zr2 and Al3Zr5 exhibit highest cathodic activity, corrosion resistance, and passivity.
Aljohani, Talal
6c638cd8-17e8-4138-b606-19fca767e2fe
Aljohani, Talal
6c638cd8-17e8-4138-b606-19fca767e2fe
Hayden, Brian
aea74f68-2264-4487-9d84-5b12ddbbb331

Aljohani, Talal (2013) High throughput synthesis and corrosion studies on alloys. University of Southampton, Chemistry, Doctoral Thesis, 197pp.

Record type: Thesis (Doctoral)

Abstract

A range of Ni-Cr, Ni-W, Al-Mg, and Al-Mg-Zr thin film alloys have been synthesised using a controllable compositional gradient method based on MBE sources allowing the deposition of compositional gradients of a large range of thin film materials. The alloy materials are characterised by X-ray diffraction, including phase identification and crystallite size, and energy dispersive x-ray spectroscopy (EDX). The corrosion resistance of 100 discrete alloy compositions has been measured simultaneously in identical environments using a high-throughput screening protocol based on cyclic voltammetry (CV). The corrosion resistances and potentials are extracted from voltametric data by both the Linear Polarisation Resistance (LPR) and Tafel Extrapolation methods. Results from these are shown to be consistent. In general, the corrosion (polarisation) resistance behaviour is shown to be directly related to the bulk alloy structures or morphologies. In the case of the NiCr alloys, besides the b.c.c ?-Cr (Im3m) phase and its Ni solid solutions, which exhibit the highest polarisation resistances, the ? Cr3Ni2 (P42/mnm) phase exhibits the next best polarisation resistance. The incorporation of W in the Ni-W solid solution at low W compositions resulted in a small reduction in corrosion resistance while a significant increase in the corrosion resistance was observed for alloy compositions greater than 24 %at. W. The best corrosion resistance of Al-Mg alloys was observed for alloy compositions comprise 35%at. Al, which corresponds to the formation of ? Al12Mg17 (i.e. also named ? phase). The incorporation of Zr in the Al-Mg resulted in forming five Al-Zr metastable phases i.e. Al3Zr, Al2Zr, Al3Zr2, Al4Zr5, and Al3Zr5. The Al-Mg-Zr alloys composition contained Al3Zr2 and Al3Zr5 exhibit highest cathodic activity, corrosion resistance, and passivity.

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Published date: 30 June 2013
Organisations: University of Southampton, Chemistry

Identifiers

Local EPrints ID: 359290
URI: https://eprints.soton.ac.uk/id/eprint/359290
PURE UUID: 46118ecf-4088-4a17-966c-68ccd189a5a6
ORCID for Brian Hayden: ORCID iD orcid.org/0000-0002-7762-1812

Catalogue record

Date deposited: 16 Dec 2013 14:13
Last modified: 06 Jun 2018 13:16

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Contributors

Author: Talal Aljohani
Thesis advisor: Brian Hayden ORCID iD

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