Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.588839
Title: High throughput synthesis and corrosion studies on alloys
Author: Aljohani, Talal
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2013
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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 α-Cr (Im3m) phase and its Ni solid solutions, which exhibit the highest polarisation resistances, the σ 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 γ Al12Mg17 (i.e. also named β 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.
Supervisor: Hayden, Brian Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.588839  DOI: Not available
Keywords: QD Chemistry
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