Solution treatment for enhanced hardness in Mo-modified Ti2AlNb-based alloys

• Published in: Journal of alloys and compounds Vol. 805; pp. 1184 - 1190
• Main Authors: Zhang, Yaran, Cai, Qi, Ma, Zongqing, Li, Chong, Yu, Liming, Liu, Yongchang
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.10.2019; Elsevier BV
• Subjects: B2 structure (crystals); Dislocations; Entanglement; Hardness; Intermetallic compounds; Intermetallic phases; Microhardness; Microstructure; Mo addition; Molybdenum; Precipitation hardening; Solution heat treatment; Solution treatment; Ti2AlNb alloys; Mo addition; Microstructure; Hardness; Solution treatment; Ti2AlNb alloys
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.07.149

The present work investigates the change in the microstructure and the improvement in the microhardness in the Mo-modified Ti2AlNb alloys induced by solution treatment. Typical Widmanstätten O + B2 structure was observed in the alloys directly aged in the O + B2 phase region, with a lower hardness value compared to that of the alloy without Mo addition. Well-arranged O + B2 colonies were observed in the specimen solution treated in single B2 phase region, and it exhibited a favorable hardness performance of up to 620 HV. Besides the precipitation hardening of the O phase, the solution of Mo in B2 phase should be responsible for the enhancement of hardness. Further microstructural observation proved that the substitution of Mo for Nb in the lattice of B2 phase induced the lattice distortion mainly the (200) and (211) planes, and the induced entanglement of dislocations also contributed to the enhancement of hardness. [Display omitted] •Well-arranged O + B2 structure is obtained in Ti2AlNb alloys by Mo addition.•Solution treatment and ageing enhanced hardness of Mo-modified Ti2AlNb alloys.•Lattice distortion of B2, especially along (211) face, is induced by adding Mo.•Orientation relationship of (211)B2//(261¯)O is identified in the aged Ti2AlNb alloy.