TY - JOUR
T1 - Breaking the high-temperature strength-ductility trade-off in TiAl alloys through microstructural optimization
AU - Zheng, Guoming
AU - Tang, Bin
AU - Zhao, Songkuan
AU - Wang, Jun
AU - Xie, Yizhen
AU - Chen, Xiaofei
AU - Wang, William Yi
AU - Liu, Dong
AU - Yang, Rui
AU - Li, Jinshan
N1 - Publisher Copyright:
© 2023
PY - 2023/11
Y1 - 2023/11
N2 - Designing a novel microstructure with higher strength-ductility than lamellar microstructure (LM), which has been considered the most valuable engineering application in the service temperature range, is desired for lightweight TiAl alloys. Our prior publication reported a three-phase tri-modal (T-T) structure for Ti-43.5Al-4Nb-1Mo-0.1B(.at%) with superior mechanical properties than LM at room temperature (Ref: Acta Mater. 225 (2022) 117,585). However, its strength-ductility at working temperature has yet to be fully exploited. This work fills the much-needed gap. The qualitative and quantitative optimizations indicate that the T-T structure's yield strength increases first and then decreases with increasing pearlitic-like microstructure (PM, which consist of three-phase (α2, γ and βo phase) with clear orientation relationships that form in a lamellar/cellular manner) content while the ductility keeps rising. When the T-T structure contains ∼20 % PMs, it exhibits a yield strength about 130MPa higher than LM coupling with doubled ductility at 750 °C. PMs can induce a prominent twinning induced plasticity and dislocation jog dragging (TWIP&DJD) effect, resulting in better strength-ductility below 700°C; above this temperature, the TWIP&DJD effect significantly plasticizes the alloys. The higher strength of the T-T structure at 750 °C is caused by hetero-deformation-induced strengthening between LMs and PMs, which cannot be offset by the plasticizing caused by PM when the volume fraction of PMs is less than 50 %. This study demonstrates that introducing an appropriate amount of plasticizing structures (similar to PM) with excellent work hardening capacity is a promising strategy for enhancing the strength-ductility synergy of TiAl and possibly other brittle materials.
AB - Designing a novel microstructure with higher strength-ductility than lamellar microstructure (LM), which has been considered the most valuable engineering application in the service temperature range, is desired for lightweight TiAl alloys. Our prior publication reported a three-phase tri-modal (T-T) structure for Ti-43.5Al-4Nb-1Mo-0.1B(.at%) with superior mechanical properties than LM at room temperature (Ref: Acta Mater. 225 (2022) 117,585). However, its strength-ductility at working temperature has yet to be fully exploited. This work fills the much-needed gap. The qualitative and quantitative optimizations indicate that the T-T structure's yield strength increases first and then decreases with increasing pearlitic-like microstructure (PM, which consist of three-phase (α2, γ and βo phase) with clear orientation relationships that form in a lamellar/cellular manner) content while the ductility keeps rising. When the T-T structure contains ∼20 % PMs, it exhibits a yield strength about 130MPa higher than LM coupling with doubled ductility at 750 °C. PMs can induce a prominent twinning induced plasticity and dislocation jog dragging (TWIP&DJD) effect, resulting in better strength-ductility below 700°C; above this temperature, the TWIP&DJD effect significantly plasticizes the alloys. The higher strength of the T-T structure at 750 °C is caused by hetero-deformation-induced strengthening between LMs and PMs, which cannot be offset by the plasticizing caused by PM when the volume fraction of PMs is less than 50 %. This study demonstrates that introducing an appropriate amount of plasticizing structures (similar to PM) with excellent work hardening capacity is a promising strategy for enhancing the strength-ductility synergy of TiAl and possibly other brittle materials.
KW - High-temperature mechanical properties
KW - Microstructure design
KW - Pearlitic-like microstructure
KW - TiAl alloys
UR - http://www.scopus.com/inward/record.url?scp=85171453278&partnerID=8YFLogxK
U2 - 10.1016/j.ijplas.2023.103756
DO - 10.1016/j.ijplas.2023.103756
M3 - 文章
AN - SCOPUS:85171453278
SN - 0749-6419
VL - 170
JO - International Journal of Plasticity
JF - International Journal of Plasticity
M1 - 103756
ER -