High strength and ductility of electron beam melted β stabilized γ-TiAl alloy at 800°C

Abstract

A nearly fully dense β stabilized γ-TiAl alloy was additively manufactured by electron beam melting. The as-fabricated specimen exhibited a fine structure consisting of α2/γ colonies (<5 μm), equiaxed γ (1 μm) and βo (<1 μm) grains. The unique microstructure rendered high strength (580 MPa) and high ductility (>50%) in the sample at 800 °C. Annealing and subsequent stabilization treatments resulted in α2/γ colonies (<50 μm) with an ultrafine (20–40 nm) lamellar structure, which gave rise to high strength (770 MPa) and good ductility (6%) levels superior to those of conventional counterparts and other γ-TiAl alloys at 800 °C.