Oxygen induced crystal structure transition of martensite in Ti-Nb-Fe alloys

The role of oxygen in the martensitic transformation and corresponding mechanical properties was studied in Ti-8Nb-2Fe base alloy. Abundant hexagonal a' martensite formed in the base alloy and exhibited low strength. Oxygen induced strain field enhanced the shuffling process but hindered {11 (2) over bar}(beta)< 111 >(beta) shearing during martensitic transformation therefore distorted the hexagonal alpha' martensite to orthorhombic alpha '' martensite, causing remarkable strength enhancement. (C) 2019 Elsevier B.V. All rights reserved.