TY - JOUR
T1 - Deciphering the impact toughening mechanism of α+β titanium alloy with lamellar microstructure
T2 - From crack initiation and propagation perspectives
AU - Dai, Jinhua
AU - Tang, Bin
AU - Wang, Chuanyun
AU - Wei, Beibei
AU - Wu, Jiaqi
AU - Zhang, Chenyu
AU - Yu, Fengtian
AU - Wang, Pengwei
AU - Dong, Zixiang
AU - Li, Jinshan
AU - Zhang, Pingxiang
N1 - Publisher Copyright:
© 2025
PY - 2026/4/1
Y1 - 2026/4/1
N2 - This study deciphered the influence of lamellar α (αl) colony parameters on impact toughness of α+β titanium alloy with lamellar microstructure. α+β titanium alloy Ti-5Al-7.5V-0.5Mo-0.5Zr-0.5Si was β treated and cooled under different cooling rates to obtain αl colony with diverse morphology and size. U-notch Charpy impact test revealed that the impact toughness increased with decreased cooling rate and consequent αl colony coarsening. Impact load-displacement curves demonstrated that αl colony coarsening simultaneously enhanced both impact crack initiation energy and crack propagation energy. In the crack initiation region near U-notch, slip trace analysis indicated that coarse αl colony extended dislocation mean free path and triggered multiple slips, which facilitated plasticity prior to U-notch cracking and enhanced Wi. Furthermore, as evidenced by Focus Ion Beam-Transmission Electron Microscopy, the nucleation of {101¯2} <1¯011> twin in coarse αl colony mitigated deformation heterogeneity, acted as prismatic slip pathway, and provided sustainable dislocation sources, thereby further delaying U-notch crack initiation and enhanced Wi. Conversely, fine αl colony restrained dislocation mobility and inhibited twin nucleation, leading to inferior U-notch plasticity and resultant low Wi. From U-notch cracking to final fracture, the sustained crack blunting due to substantial plastic deformation of coarse αl along the crack path, as well as crack deflection and branching between adjacent coarse αl colonies, synergistically enhanced Wp. Conversely, fine αl colony impaired the plasticity along the crack path and restrained crack deflection, which was inconducive to Wp. In summary, αl colony coarsening played a crucial role in activating multiple toughening mechanisms during both crack initiation and propagation to achieve desirable impact toughness in α+β titanium alloys with lamellar microstructure.
AB - This study deciphered the influence of lamellar α (αl) colony parameters on impact toughness of α+β titanium alloy with lamellar microstructure. α+β titanium alloy Ti-5Al-7.5V-0.5Mo-0.5Zr-0.5Si was β treated and cooled under different cooling rates to obtain αl colony with diverse morphology and size. U-notch Charpy impact test revealed that the impact toughness increased with decreased cooling rate and consequent αl colony coarsening. Impact load-displacement curves demonstrated that αl colony coarsening simultaneously enhanced both impact crack initiation energy and crack propagation energy. In the crack initiation region near U-notch, slip trace analysis indicated that coarse αl colony extended dislocation mean free path and triggered multiple slips, which facilitated plasticity prior to U-notch cracking and enhanced Wi. Furthermore, as evidenced by Focus Ion Beam-Transmission Electron Microscopy, the nucleation of {101¯2} <1¯011> twin in coarse αl colony mitigated deformation heterogeneity, acted as prismatic slip pathway, and provided sustainable dislocation sources, thereby further delaying U-notch crack initiation and enhanced Wi. Conversely, fine αl colony restrained dislocation mobility and inhibited twin nucleation, leading to inferior U-notch plasticity and resultant low Wi. From U-notch cracking to final fracture, the sustained crack blunting due to substantial plastic deformation of coarse αl along the crack path, as well as crack deflection and branching between adjacent coarse αl colonies, synergistically enhanced Wp. Conversely, fine αl colony impaired the plasticity along the crack path and restrained crack deflection, which was inconducive to Wp. In summary, αl colony coarsening played a crucial role in activating multiple toughening mechanisms during both crack initiation and propagation to achieve desirable impact toughness in α+β titanium alloys with lamellar microstructure.
KW - Crack deflection
KW - Deformation twinning
KW - Dislocation slip
KW - Impact toughness
KW - Lamellar microstructure
KW - α+β titanium alloy
UR - https://www.scopus.com/pages/publications/105011416545
U2 - 10.1016/j.jmst.2025.05.068
DO - 10.1016/j.jmst.2025.05.068
M3 - 文章
AN - SCOPUS:105011416545
SN - 1005-0302
VL - 249
SP - 214
EP - 229
JO - Journal of Materials Science and Technology
JF - Journal of Materials Science and Technology
ER -