Newtonian viscous creep in Ti-3Al-2.5V

• Published in: Philosophical magazine (Abingdon, England) England), 2008-03, Vol.88 (9), p.1357-1367
• Main Authors: Gollapudi, Srikant, Bhosle, Vikram, Charit, Indrajit, Murty, K. Linga
• Format: Article
• Language: English
• Subjects: Coble; Condensed matter: structure, mechanical and thermal properties; Creep; Cross-disciplinary physics: materials science; rheology; Deformation, plasticity, and creep; diffusion; Exact sciences and technology; HRTEM; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; microscopy; Physics; slip band; Spingarn-Nix model; titanium alloys; transmission electron; Treatment of materials and its effects on microstructure and properties
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430802144154

Biaxial creep tests were performed on fine-grained Ti-3Al-2.5V tubing at 823 and 873 K in the stress range σ/E  = 1.7  × 10 −4 to σ/E  = 5.9  × 10 −4 . Subsequently, the creep data were analysed to determine the stress exponent and activation energy. A stress exponent value of 1 and an activation energy equal to that for grain boundary diffusion were suggestive of a Coble creep-controlled deformation regime. However, discrepancy between the experimental creep rates and Coble creep model predictions along with subsequent observation of deformed microstructures decorated with slip bands implied the operation of a different viscous creep mechanism. A slip band model proposed by Spingarn and Nix was found to provide a better description of the experimental strain rates rather than the conventional viscous creep mechanisms. High-resolution transmission electron microscopy studies confirmed the nature of these bands.