Multi-step heat treatment design for nano-scale lamellar structures of a cast Ti-45Al-8.5Nb-(W, B, Y) alloy. (December 2016)

• Record Type: Journal Article
• Authors: Qiang, Fengming; Kou, Hongchao; Yang, Guang; Tang, Bin; Li, Jinshan
• Is Part Of: Intermetallics. Volume 79(2016:Dec.)
• Page Start: 35
• Page End: 40
• Publication Date: 2016-12
• Subjects: Titanium aluminides -- Heat treatment -- Segregation -- Lamellar structure -- Phase transformation; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2016.09.006
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: A multi-step heat treatment is proposed to optimize the lamellar structure of as-cast high Nb containing TiAl alloys. The β-segregation is removed effectively after the first two step heat treatment, a short-time holding within β single phase field then annealing in α+β phase field. During the third step heat treatment, a subsequent low-temperature aging, new γ lamellae precipitate by the means of isolated nucleation or twin-related nucleation. After the proposed multi-step heat treatment, the alloy presents nano-scaled lamellar structure with the colony size about 140 μm. Graphical abstract: Highlights: A novel idea for lamellar structure optimization is proposed. A nano-scaled lamellar structure with nearly no β-segregation is obtained. Microstructure evolution and phase transformation of Ti-45Al-8.5Nb-(W, B, Y) alloy is studied.