Surface characterization of thermally oxidized Ti-6Al-7Nb alloy

• Published in: Materials chemistry and physics Vol. 171; pp. 374 - 378
• Main Authors: Aniołek, K., Kupka, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2016
• Subjects: Adhesion; Adhesive strength; Biomaterials; Modulus of elasticity; Oxidation; Oxides; Strength; Surface properties; Temperature; Titanium base alloys; Titanium dioxide; Surface properties; Oxides; Oxidation; Adhesion; Biomaterials
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2016.01.031

The paper presents a structural and mechanical characterization of oxide layer obtained on Ti-6Al-7Nb alloy in the process of isothermal oxidation (TO). The oxidation was carried out at the temperature of 600 °C during 72 h, in the air atmosphere. The phase composition, morphology, nanohardness, Young's modulus and the adhesion strength of the obtained scale were determined. It has been found that the oxide layer was a mixture of TiO2 oxides in the form of anatase and rutile and also of niobium oxide NbO and featured more than twice higher hardness and higher Young's modulus as compared to the Ti-6Al-7Nb alloy in the as-received state (AR). Values of critical loads, being the measure of the scale adhesion strength, were determined in a scratch test. The first damage to the oxide layer was observed at the load of 7.6 N and a total delamination was found at the load of 65.9 N. •Oxidation at 600 °C for 72 h resulted in the formation of an exterior layer of TiO2, NbO.•TO-treated Ti-6Al-7Nb achieved higher surface hardness and abrasion resistance.•The adhesion force of the oxide to the substrate was approximately 45 N.