Orthorhombic martensite formation upon aging in a Ti-30Nb-4Sn alloy

Author(s)

Salvador, Camilo A. F. ; Lopes, Eder S. N. ; Ospina, Carlos A. ; Caram, Rubens

• Document type: Journal article
• Source: Materials Chemistry and Physics; v. 183, p. 238-246, NOV 1 2016.
• Web of Science Citations: 5

Abstract

The characteristics of orthorhombic martensite (alpha `') formed by step-quenching in a Ti-30Nb-4Sn (wt%) alloy have been investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). According to literature, alpha `' lattice parameters depend mainly on the composition of the parent 3 phase. In this study, samples subjected to step quenching heat treatment presented alpha `' phase formation in the proximity of alpha phase laths, driven by two combined factors: solute rejection and lattice strain. Our results indicate that as the aging is prolonged, alpha `' becomes richer in solute content, which makes it more similar to the parent alpha phase. An average 2.55% lattice strain along {[}110]beta directions was found to be necessary in order to obtain alpha `' from the beta phase after 24 h of aging at 400 degrees C, followed by water-quenching. The initial lattice strain along the same direction was estimated at approximately 3.60% with zero aging time. The precipitation of the alpha phase does not inhibit a solute rich alpha `' phase formation. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/50391-6 - Non-classical mechanisms of solid-state precipitation in Ti alloys
• Grantee: Rubens Caram Junior
• Support type: Regular Research Grants
• FAPESP's process: 12/10164-8 - Alpha phase nucleation during isothermal aging heat treatments in Ti-Nb and Ti-Nb-Sn alloys
• Grantee: Camilo Augusto Fernandes Salvador
• Support type: Scholarships in Brazil - Master