Oxide-scale and Α-casing Characterization in Ti₆Al₄V Alloy Oxidised in Oxygen Gas

Abstract

Characterization of oxide scale and α-casing in Ti6Al4V titanium alloy oxidized at 1050, 1150, 1250 and 1340 K for 2, 4, 6, 8 and 12 h in a dynamic oxygen gas atmosphere has been analyzed. the oxide scale exhibited a spalling tendency. Its thickness systematically increased with the temperature and the duration of the oxidation. at a later stage the scale exhibited a catastrophic growth due to the increased porosity. the oxygen stabilized α-phase and its volume fraction as well as its hardness decreased with the distance in the metal matrix (α-casing). Estimated oxygen diffusion coefficients based on the hardness profiles across α-casing were 7.0 x 10-14, 8.5 x 10-14, and 1.2 x 10-13, 1.8 x 10-13 m2/s at 1050, 1150, 1250, and 1340 K, respectively. Similarly, the overall activation energy for diffusion of oxygen in the alloy was 105 kJ mol-1. EDS analysis across α-casing in the internal oxidation zone revealed sharp concentration wells for Ti and Al. Titanium concentration decreased and that of aluminum increased in these wells.

Department(s)

Materials Science and Engineering

Keywords and Phrases

Ti6Al4V; Oxide Scale; Titanium alloys

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2006 Carl Hanser Verlag, All rights reserved.

Publication Date

01 Jan 2006

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