Effect of microstructure on Ti₃Al precipitation during ageing of Ti-6Al-4V alloy

^a Department of Materials Engineering, São Carlos School of Engineering, University of São Paulo, São Carlos, Brazil
^b Chair of Functional Materials, Saarland University, Saarbrücken, Germany

^* bruna2.callegari@usp.br

Abstract

The aim of the present work is to explore the age-hardening potential of Ti-6Al-4V (Ti-64) alloy with variation of the starting microstructure, with attention to the precipitation of nano-sized Ti3Al phase, as influenced by microstructural features. The alloy was either solution-treated or deformed by compression at temperatures above and below its β-transus to produce microstructures comprising martensitic, lamellar and globular α morphologies, as well as the existence or absence of β phase, and subsequently submitted to ageing treatments at 400°C/8h using in situ x-ray diffraction. Precipitated fractions of Ti₃Al were obtained via Rietveld refinement and aged microstructures were characterized by micro-hardness measurements. Results show that α₂ precipitation is favored by a globular morphology of α and hindered by a martensitic α morphology, and suggest that the presence of β phase also has as influence on precipitation.