Dynamic recrystallization behavior of an as-cast TiAl alloy during hot compression

Journal Article · Sat Nov 15 04:00:00 EST 2014 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2014.09.013· OSTI ID:22403595

Li, Jianbo ^[1]; Liu, Yong ^[1]; Wang, Yan ^[2]; Liu, Bin ^[1]; He, Yuehui ^[1]

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1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)
2. School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China)

High temperature compressive deformation behaviors of as-cast Ti–43Al–4Nb–1.4W–0.6B alloy were investigated at temperatures ranging from 1050 °C to 1200 °C, and strain rates from 0.001 s{sup −1} to 1 s{sup −1}. Electron back scattered diffraction technique, scanning electron microscopy and transmission electron microscopy were employed to investigate the microstructural evolutions and nucleation mechanisms of the dynamic recrystallization. The results indicated that the true stress–true strain curves show a dynamic flow softening behavior. The dependence of the peak stress on the deformation temperature and the strain rate can well be expressed by a hyperbolic-sine type equation. The activation energy decreases with increasing the strain. The size of the dynamically recrystallized β grains decreases with increasing the value of the Zener–Hollomon parameter (Z). When the flow stress reaches a steady state, the size of β grains almost remains constant with increasing the deformation strain. The continuous dynamic recrystallization plays a dominant role in the deformation. In order to characterize the evolution of dynamic recrystallization volume fraction, the dynamic recrystallization kinetics was studied by Avrami-type equation. Besides, the role of β phase and the softening mechanism during the hot deformation was also discussed in details. - Highlights: • The size of DRXed β grains decreases with increasing the value of the Z. • The CDRX plays a dominant role in the deformation. • The broken TiB{sub 2} particles can promote the nucleation of DRX.

• OSTI ID: 22403595
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 97; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
BACKSCATTERING
BORON ALLOYS
DEFORMATION
ELECTRON DIFFRACTION
FLOW STRESS
MICROSTRUCTURE
NIOBIUM ALLOYS
NUCLEATION
RECRYSTALLIZATION
SCANNING ELECTRON MICROSCOPY
STRAIN RATE
STRAINS
TITANIUM ALLOYS
TITANIUM BORIDES
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN ALLOYS