Impact toughness, crack initiation and propagation mechanism of Ti6422 alloy with multi-level lamellar microstructure

Abstract

The influence of different solution and aging conditions on the microstructure, impact toughness, and crack initiation and propagation mechanisms of the novel α + β titanium alloy Ti6422 was systematically investigated. By adjusting the furnace cooling time after solution treatment and the aging temperature, Ti6422 alloy samples were developed with a multi-level lamellar microstructure, including microscale α colonies and α_p lamellae, as well as nanoscale α_s phases. Extending the furnace cooling time after solution treatment at 920°C for 1 h from 240 to 540 min, followed by aging at 600°C for 6 h, increased the α_p lamella content, reduced the α_s phase content, expanded the α colonies and α_p lamellae size, and improved the impact toughness from 22.7 to 53.8 J/cm². Additionally, under the same solution treatment, raising the aging temperature from 500 to 700°C resulted in a decrease in the α_s phase content and a growth in the thickness of the α_p lamella and α_s phase. The impact toughness increased significantly with these changes. Samples with high α_p lamellae content or large α_s phase size exhibited high crack initiation and propagation energies. Impact deformation caused severe kinking of the α_p lamellae in crack initiation and propagation areas, leading to a uniform and high-density kernel average misorientation (KAM) distribution, enhancing plastic deformation coordination and uniformity. Moreover, the multidirectional arrangement of coarser α colonies and α_p lamellae continuously deflect the crack propagation direction, inhibiting crack propagation.

Keywords

novel titanium alloy / multi-level lamellar microstructure / impact toughness / crack initiation and propagation

References

[1] Banerjee D, Williams JC. Perspectives on titanium science and technology. Acta Mater., 2013, 613844

[2] Zhang XS, Chen YJ, Hu JL. Recent advances in the development of aerospace materials. Prog. Aerosp. Sci., 2018, 97: 22

[3] Wu D, Wang WL, Zhang LG, Wang ZY, Zhou KC, Liu LB. New high-strength Ti–Al–V–Mo alloy: From high-throughput composition design to mechanical properties. Int. J. Miner. Metall. Mater., 2019, 2691151

[4] Ritchie RO. The conflicts between strength and toughness. Nat. Mater., 2011, 1011817

[5] Lin Y, Yu Q, Pan J, Duan FH, Ritchie RO, Li Y. On the impact toughness of gradient-structured metals. Acta Mater., 2020, 193: 125

[6] Wang R, Song X, Wang Let al.. New role of a phase in the fracture behavior and fracture toughness of a β-type bio-titanium alloy. Int. J. Miner. Metall. Mater., 2023, 3091756

[7] L. Lei, Y.Q. Zhao, Q.Y. Zhao, et al., Impact toughness and deformation modes of Ti–6Al–4V alloy with different microstructures, Mater. Sci. Eng. A, 801(2021), art. No. 140411.

[8] L. Lei, Q.Y. Zhao, Y.Q. Zhao, et al., Study on the intrinsic factors determining impact toughness of TC21 alloy, Mater. Charact., 177(2021), art. No. 111164.

[9] Launey ME, Ritchie RO. On the fracture toughness of advanced materials. Adv. Mater., 2009, 21202103

[10] Zhang F, Zeng WD, Zhang PH, Ma HY, Xu JW. Simultaneous enhancements of strength and toughness by multiscale lamellar structure in Ti₂AlNb based intermetallic. J. Mater. Sci. Technol., 2024, 174: 249

[11] Buirette C, Huez J, Gey N, Vassel A, Andrieu E. Study of crack propagation mechanisms during Charpy impact toughness tests on both equiaxed and lamellar microstructures of Ti–6Al–4V titanium alloy. Mater. Sci. Eng. A, 2014, 618: 546

[12] C. Wu, Y.Q. Zhao, S.X. Huang, et al., Microstructure tailoring and impact toughness of a newly developed high strength Ti–5Al–3Mo–3V–2Cr–2Zr–1Nb–1Fe alloy, Mater. Charact., 175(2021), art. No. 111103.

[13] X.Y. Zhang, W.J. Jia, and X.N. Mao, Effect of microstructure on the tensile properties and impact toughness of TC21G titanium alloy, Mater. Charact., 185(2022), art. No. 111752.

[14] W.G. Zhu, J. Lei, B. Su, and Q.Y. Sun, The interdependence of microstructure, strength and fracture toughness in a novel β titanium alloy Ti–5Al–4Zr–8Mo–7V, Mater. Sci. Eng. A, 782(2020), art. No. 139248.

[15] Fan JK, Li JS, Kou HC, Hua K, Tang B. The interrelationship of fracture toughness and microstructure in a new near β titanium alloy Ti–7Mo–3Nb–3Cr–3Al. Mater. Charact., 2014, 96: 93

[16] Huang SX, Zhao QY, Zhao YQet al.. Toughening effects of Mo and Nb addition on impact toughness and crack resistance of titanium alloys. J. Mater. Sci. Technol., 2021, 79: 147

[17] Zheng XD, Zheng SJ, Wang Jet al.. Twinning and sequential kinking in lamellar Ti–6Al–4V alloy. Acta Mater., 2019, 181: 479

[18] Shen J, Zhang ZH, Xie JX. Simultaneously enhancing the hot workability and room-temperature strength of Ti–6Al–4 V alloy via adding Mo and Fe. J. Mater. Sci. Technol., 2024, 180: 32

[19] Shen J, Zhang ZH, Xie JX. Hot deformation behavior and mechanism of Ti–6Al–4V–2Mo–2Fe titanium alloy with satisfactory hot workability. Metall. Mater. Trans. A, 2023, 54104053

[20] J. Shen, Z.H. Zhang, and J.X. Xie, Annealing microstructure evolution and strength-plasticity enhancement mechanism of a novel titanium alloy Ti6422, Mater. Sci. Eng. A, 897(2024), art. No. 146338.

[21] H. Wang, S.W. Xin, Y.Q. Zhao, W. Zhou, and W.D. Zeng, Plane strain fracture behavior of a new high strength Ti–5Al–3Mo–3V–2Zr–2Cr–1Nb–1Fe alloy during heat treatment, Mater. Sci. Eng. A, 797(2020), art. No. 140080.

[22] Gao Y, Zhang C, Zhang JZ, Lu X. Microstructure evolution and strengthening mechanism of high-performance powder metallurgy TA15 titanium alloy by hot rolling. Int. J. Miner. Metall. Mater., 2024, 3161426

[23] H. Wang, Y.Q. Zhao, Q.Y. Zhao, S.W. Xin, W. Zhou, and W.D. Zeng, Microstructure evolution and fracture behavior of Ti–5Al–3Mo–3V–2Zr–2Cr–1Nb–1Fe alloy during BASCA heat treatments, Mater. Charact., 174(2021), art. No. 110975.

[24] Zhang RQ, Zhao QY, Guo DZet al.. High impact toughness of CT20 alloy induced by multi-factor coupling. J. Mater. Sci. Technol., 2024, 192: 65

[25] X. Wen, M.P. Wan, C.W. Huang, et al., Effect of microstructure on tensile properties, impact toughness and fracture toughness of TC21 alloy, Mater. Des., 180(2019), art. No. 107898.

[26] Lan L, Xin RY, Jin XY, Gao S, He B. Influence of multiple laser shock peening treatments on the microstructure and mechanical properties of Ti–6Al–4V alloy fabricated by electron beam melting. Int. J. Miner. Metall. Mater., 2022, 2991780

[27] Huang CW, Wang FM, Wen Xet al.. Tensile performance and impact toughness of Ti-55531 alloy with multilevel lamellar microstructure. J. Mater. Sci., 2021, 56148848

[28] J.X. Wang, X.W. Ye, Y.H. Li, et al., Effect of annealing temperature on mechanical properties of TC21 titanium alloy with multilevel lamellar microstructure, Mater. Sci. Eng. A, 869(2023), art. No. 144788.

[29] Li M, Shi ZZ, Wang Q, Cheng Y, Wang LN. Zn-0.8Mn alloy for degradable structural applications: Hot compression behaviors, four dynamic recrystallization mechanisms, and better elevated-temperature strength. J. Mater. Sci. Technol., 2023, 137: 159

[30] Duan QQ, Qu RT, Zhang P, Zhang ZJ, Zhang ZF. Intrinsic impact toughness of relatively high strength alloys. Acta Mater., 2018, 142: 226

[31] Tan CS, Sun QY, Xiao L, Zhao YQ, Sun J. Slip transmission behavior across α/β interface and strength prediction with a modified rule of mixtures in TC21 titanium alloy. J. Alloy. Compd., 2017, 724: 112

[32] W.G. Zhu, J. Lei, C.S. Tan, et al., A novel high-strength β-Ti alloy with hierarchical distribution of α-phase: The superior combination of strength and ductility, Mater. Des., 168(2019), art. No. 107640.

[33] He D, Zhu JC, Zaefferer S, Raabe D. Effect of retained beta layer on slip transmission in Ti–6Al–2Zr–1Mo–1V near alpha titanium alloy during tensile deformation at room temperature. Mater. Des., 2014, 56: 937

[34] Daniel R, Meindlhumer M, Baumegger Wet al.. Grain boundary design of thin films: Using tilted brittle interfaces for multiple crack deflection toughening. Acta Mater., 2017, 122: 130

RIGHTS & PERMISSIONS

University of Science and Technology Beijing