Advanced Powder Technology, Vol.28, No.7, 1719-1726, 2017
Dual structure O+B2 for enhancement of hardness in furnace-cooled Ti2AlNb-based alloys by powder metallurgy
Powder metallurgic Ti2AlNb alloys were sintered at 900 degrees C, 990 degrees C, 1060 degrees C, and 1100 degrees C (i.e. in the O + B2, alpha(2) + B2 + O, alpha(2) + B2, and B2 phase region, respectively) for 12 h, followed by water quenching and furnace cooling. Quenching was employed to reserve the high-temperature phase and microstructure, and furnace cooling aimed to regulate the room-temperature microstructure for the enhancement of hardness. Widmanstatten B2 + O structure, which contributes to the properties, was induced from B2 crystals by sintering, unless the alloy was treated in the alpha(2) + B2 phase region. With the elevation of the sintering temperature, the content of alpha(2) phase became lower in the furnace-cooled alloys, and the hardness was improved accordingly. The highest hardness performance, 389 +/- 23 HV, was obtained in the alloy solution treated in the single B2 region, and the alloy was comprised of complete O + B2 Widmanstatten structure. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.