Electrochemistry and passivity of Ti-15 V-3 Cr-3 Al-3 Sn [beta]-titanium alloy in ambient temperature aqueous chloride solutions

Journal Article · Sat Oct 01 00:00:00 EDT 1994 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2059146· OSTI ID:7183335

Kolman, D G; Scully, J R ^[1]

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1. Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering

Examination of the electrochemical behavior of Ti-15 V-3 Cr-3 Al-3 Sn (Ti-15-3) alloy was performed as an initial step in understanding mechanism for environmentally assisted cracking of [beta]-titanium alloys in room temperature aqueous chloride solutions. both solution heat-treated (SHT) and peak-aged (PA) Ti-15-3 were studied, in addition to SHT commercially pure Ti (grade 2 Ti) and Ti-5 Al-2.5 Sn (grade 6 Ti). The latter roughly models [alpha] precipitates within the [beta]-titanium matrix in Pa Ti-15-3. Anodic polarization studies in 0.6M NaCl and 0.6M NaCl adjusted to pH 1 with HCl revealed that Ti-15-3 was spontaneously passive in each solution, with no observed pitting potential at potentials as positive as 2.1 V vs. SCE. However, an active/passive transition was observed on all alloys in both aerated and deaerated 5M HCl. In situ characterization of passivity by electrochemical impedance spectroscopy confirmed that passive film growth was linear with potential above primary passivation potentials in all solutions, and that the passive dissolution rate is limited by the charge-transfer reaction, especially at lower potentials. Similar passive current densities, active/passive transition potentials, and apparent oxide resistivities on SHT and PA Ti-15-3 suggest little effect of the [alpha] precipitate on the passive behavior of PA Ti-15-3. Auger electron spectroscopy and hydrogen evolution kinetics suggested less than stoichiometric incorporation of alloying additions into the passive film of Ti-15-3. X-ray photoelectron spectroscopy indicated that, to the limited extent that alloying additions are found in the passive film, they are oxidized. The valence states present are discussed. Predominantly TiO[sub 2] passive films may explain the similar passive electrochemical behaviors observed on the materials examined.

• OSTI ID: 7183335
• Journal Information: Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 141:10; ISSN JESOAN; ISSN 0013-4651
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400 -- Electrochemistry
ALKALI METAL COMPOUNDS
ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CHROMIUM ALLOYS
COATINGS
CORROSION
CORROSION RESISTANCE
CORROSIVE EFFECTS
CRACK PROPAGATION
ELECTROCHEMICAL CORROSION
HALIDES
HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PASSIVATION
PROTECTIVE COATINGS
SODIUM CHLORIDES
SODIUM COMPOUNDS
TIN ALLOYS
TITANIUM ALLOYS
TITANIUM BASE ALLOYS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
USES
VANADIUM ALLOYS