TY - JOUR
T1 - Continuous cooling transformation (CCT) behavior of a high Nb-containing TiAl alloy
AU - Yang, Jieren
AU - Cao, Bei
AU - Wu, Yulun
AU - Gao, Zitong
AU - Hu, Rui
N1 - Publisher Copyright:
© 2018 Acta Materialia Inc.
PY - 2019/3
Y1 - 2019/3
N2 - The continuous-cooling-transformation (CCT) diagram is significant to the microstructural design and the control of mechanical properties. The CCT behavior of a high Nb-containing TiAl alloy was experimentally investigated in the present study. Samples with the nominal composition of Ti-45Al-8.5Nb-(W, B, Y) (at.%) were isothermally held at 1500 °C (in the single β phase field) and subsequently cooled at different cooling rates. Based on the samples quenched from high temperatures, the microstructures during continuous cooling was characterized and the CCT diagram was established and evaluated. With the increase of cooling rate (5, 20, 100, 700 K/min), the phase transformation presented a lagging behavior comparing with the equilibrium phase diagram. Meanwhile, the decomposition of high-temperature β/B2 phase was incomplete at large cooling rate, indicating that a fully lamellar (FL) microstructure alloy can be obtained only below a critical cooling rate. Further, the discontinuously coarsened γ phase, the crystalline orientations of precipitated block γ and ω particles in B2 region were characterized and the phase transformation mechanisms were discussed.
AB - The continuous-cooling-transformation (CCT) diagram is significant to the microstructural design and the control of mechanical properties. The CCT behavior of a high Nb-containing TiAl alloy was experimentally investigated in the present study. Samples with the nominal composition of Ti-45Al-8.5Nb-(W, B, Y) (at.%) were isothermally held at 1500 °C (in the single β phase field) and subsequently cooled at different cooling rates. Based on the samples quenched from high temperatures, the microstructures during continuous cooling was characterized and the CCT diagram was established and evaluated. With the increase of cooling rate (5, 20, 100, 700 K/min), the phase transformation presented a lagging behavior comparing with the equilibrium phase diagram. Meanwhile, the decomposition of high-temperature β/B2 phase was incomplete at large cooling rate, indicating that a fully lamellar (FL) microstructure alloy can be obtained only below a critical cooling rate. Further, the discontinuously coarsened γ phase, the crystalline orientations of precipitated block γ and ω particles in B2 region were characterized and the phase transformation mechanisms were discussed.
KW - CCT diagram
KW - Cooling rate
KW - Microstructure
KW - Phase transformation
KW - TiAl alloy
UR - http://www.scopus.com/inward/record.url?scp=85061040222&partnerID=8YFLogxK
U2 - 10.1016/j.mtla.2018.11.018
DO - 10.1016/j.mtla.2018.11.018
M3 - 文章
AN - SCOPUS:85061040222
SN - 2589-1529
VL - 5
JO - Materialia
JF - Materialia
M1 - 100169
ER -