The Microstructural and Phase Evolution of the 3D Printed Ti–6Al–4V Alloy during Mechanical Loading

Abstract

This paper presents the results of an in situ study on the evolution of the microstructure and phase composition of 3D-printed Ti–6Al–4V samples under tension in the transmission electron microscope col-umn. The microstructure of Ti–6Al–4V specimens manufactured by wire-feed electron beam additive tech-nology is shown to consist of columnar primary β-grains inside of which are α/α'-Ti laths separated by layers of the residual β-phase and gathered into packets. A characteristic feature of 3D-printed Ti–6Al–4V samples is the concentration nonuniformity of the alloying elements due to the partial decomposition of the marten-sitic α'-phase. The reorientation of the α/α'-Ti lattice near interfaces takes place during uniaxial tension. Deformation-induced α'→α" transformations can develop in the reoriented regions of the α/α'-Ti lattice, in places enriched in vanadium.