A high-performance β-stabilized Ti-43Al-9V-0.2Y alloy sheet with a nano-scaled antiphase domain

A novel β-stabilized Ti-43Al-9V-0.2Y alloy sheet with a nano-scaled antiphase domain (APD) microstructure and excellent performance was fabricated via hot-pack rolling in the (α + γ) phase region (1260 °C). Owing to the temperature drop and reheat associated with multi-pass rolling, heterogeneous and regular APD-mixed lamellar structures formed with the occurrence of α → β + γ and α → α₂ + γ phase transformations. The antiphase boundary (APB) between two nano-scaled APD structures (average size: ∼15 nm) is identified as a type of atomic shift, which is induced by the disorder-order transformation in the α₂ phase. Moreover, compared with the corresponding as-forged alloy and other hot-working β-stabilized TiAl alloys, the current alloy sheet exhibited higher strength both at room and elevated temperatures. The improvement in the tensile properties is attributed mainly to the duplex microstructure consisting of fine nano-scaled APD/lamella mixed structures.