Microstructural evolution of ω assisted α precipitates in β-CEZ alloy during ageing process

Journal Article · Sun Apr 15 04:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.01.056· OSTI ID:22804944

He, Tao; Feng, Yong ^[1]; Luo, Wenzhong ^[2]; He, Yongsheng ^[1]; Tian, Lin; Lai, Yunjin ^[2]

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1. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072 (China)
2. NLEL for special titanium alloy material manufacturing, Western Superconducting Technology Co., Ltd., Xi'an, Shaanxi 710018 (China)

Highlights: • Ultrafine Athermal ω precipitates were formed in β-CEZ alloy by quenching from above the β transus temperature. • In the ageing process, these ω precipitates coarsen, accompanied by the form of needle-like α phase. • ω precipitates were formed by {111}β planes shift 0.5d222 along the direction. • The superfine α particles are formed in close proximity of the ω/β interface. - Abstract: The microstructural evolution in β-CEZ (Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe wt%) alloy, after quenching and ageing, has been investigated by combining results from orientation imaging microscopy, transmission electron microscopy, high-resolution TEM (HRTEM). Ultrafine Athermal ω precipitates (about 1 nm) are formed in this alloy by quenching from above the β transus temperature. In the ageing process, these ω precipitates coarsen, accompanied by the form of needle-like α phase. The scale of ω assisted α increased from 5 to 10 nm in width and about 50 nm in length to 10 nm in width and 100–300 nm in length while extending ageing time from 2 h to 5 h at 350 °C. However, when going on extending the ageing time from 5 h to 20 h at 350 °C, the scale of α didn't grow dramatically but the density of α increased clearly. When increasing the ageing temperature from 350 °C to 450 °C, the scale of ω assisted α grow dramatically. Furthermore, the structural relationship of ω and α is observed by HRTEM images. It can be found that ω precipitates were formed by {111}β planes shift 0.5d222 along the <111> direction, and the superfine α particles are formed in close proximity of the ω/β interface.

• OSTI ID: 22804944
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 138; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
ALLOY SYSTEMS
ALUMINIUM COMPOUNDS
CHROMIUM COMPOUNDS
INTERFACES
IRON COMPOUNDS
MICROSTRUCTURE
MOLYBDENUM COMPOUNDS
ORIENTATION
PARTICLES
PRECIPITATION
RESOLUTION
TIN COMPOUNDS
TITANIUM COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
ZIRCONIUM COMPOUNDS