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Cathodic deoxygenation of the alpha case on titanium and alloys in molten calcium chloride

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Abstract

The oxygen-enriched alpha case on titanium and alloys was successfully deoxygenated to satisfactory levels by electrolysis in molten CaCl2, in which the cathode was made from the metal to be refined. The oxygen distribution in the metal before and after electrolysis was characterized by microhardness tests, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The electrolysis has been carried out at voltages sufficiently below that for the decomposition of CaCl2, and the results obtained suggest that the alpha case deoxygenation follows a simple oxygen ionization mechanism in which the oxygen in the metal is simply ionized at the cathode/electrolyte interface, dissolves in the molten salt, and then discharges at the anode. It is shown that by applying the electrochemical method, the alpha cases on both commercially pure titanium (CP Ti) and the Ti-6Al-4V alloy can be effectively deoxygenated. In particular, due to the removal of oxygen, the original alpha case (single phase) on the Ti-6Al-4V alloy has been converted back to the two-phase microstructure.

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Author notes

  1. Tom W. Farthing (Technical Director)

    Present address: Timet UK Ltd., B6 7UR, West Midland, United Kingdom

Authors and Affiliations

  1. the Department of Materials Science and Metallurgy, University of Cambridge, CB2 3QZ, Cambridge, United Kingdom

    George Zheng Chen (Assitant Director of Research) & Derek J. Fray (Head of Department and Professor of Materials Chemistry)

  2. SO24 0NJ, Alresford, England

    Tom W. Farthing (Technical Director)

Authors
  1. George Zheng Chen
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  2. Derek J. Fray
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  3. Tom W. Farthing
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Chen, G.Z., Fray, D.J. & Farthing, T.W. Cathodic deoxygenation of the alpha case on titanium and alloys in molten calcium chloride. Metall Mater Trans B 32, 1041–1052 (2001). https://doi.org/10.1007/s11663-001-0093-8

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  • DOI: https://doi.org/10.1007/s11663-001-0093-8

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