Microstructure and mechanical properties of a high-oxygen core-shell network structured Ti6Al4V alloy

Fully dense core-shell (CS) structured Ti-6Al-4V (Ti64) compact was synthesized by spark plasma sintering (SPS) from oxidized Ti64 powder. Microstructure characterization and compositional analyses show that the shell is with near single alpha phase and the core is composed of alpha lamellae packed by beta phase with a continuous beta phase in between. Phase transformation from (alpha+beta) phase to a near single alpha phase in shell is attributed to oxygen penetration, thereby forming such a novel CS structure. The CS Ti64 compact exhibits a yield strength of about 1260 MPa and a fracture elongation of 13%. Such excellent mechanical properties are attributed to solid strengthening of oxygen and the unique core-shell structure. The mechanical properties can be further enhanced by manipulating the microstructure in core and shell via heat treatment. (C) 2017 Elsevier Ltd. All rights reserved.