本研究旨在探討亞穩態β鈦合金Ti-10V-2Fe-3Al (以下本文簡稱Ti-1023)在表層生成α-case組織下對熱壓縮變形行為之影響。基於Ti-O關係圖得知鈦合金於400 °C以上高溫環境將有所相變化，故於大氣環境以加熱爐進行不同熱處理條件下之均質化處理，顯示於900 °C退火5小時後材料部分β相轉換為α相，α-case於表面生成且同時深層組織均質化。其中分析熱處理溫度700 °C - 900 °C之大氣環境退火5 - 24小時對α-case厚度生成之影響，試片重量隨溫度與時間增加而上升，熱重分析表明材料氧化動力多處於拋物線狀態，並由光學顯微鏡(Optical Microscope, OM)、電子微探儀(Electron Probe Micro-Analyzer, EPMA)及奈米壓痕(Nano Indenter)定量α-case之厚度，以Fick’s Law描述其氧擴散濃度及硬度對深度之關聯，確立不同熱處理條件下α-case厚度與其氧於Ti-1023內之擴散係數，實驗結果顯示隨熱處理溫度與時間的增加α-case厚度隨之增厚，而擴散係數僅受溫度影響；另一方面以有限元素軟體模擬氧於高溫大氣中於Ti-1023之擴散，平均絕對百分比誤差(Average Absolute Relative Error, AARE) 3.67 %對比驗證Fick’s Law所描述之氧擴散實驗曲線，表明模擬模型可供初步估算α-case厚度。再者，藉由真實應力-應變曲線與微觀組織演化分析表層具300 μm厚α-case (900 °C/5 hrs)之均質化Ti-1023於壓縮溫度(700 °C - 900 °C)、應變率(0.01 s-1 - 1 s-1)及壓縮應變量(20 % - 60 %)等不同熱鍛條件下，闡明高溫變形過程中α-case的存在對材料變形與裂紋產生之相互作用。最後，建立α-case影響變形與裂紋生長機制。

The effect of oxygen-enriched surface layer on hot compression behavior of near β titanium alloy Ti-10V-2Fe-3Al (Ti-1023) was investigated in this present study.Based on the Ti-O diagram, titanium alloy is known that phase change in an elevated temperature environment above 400 °C, thus different heat treatment conditions in a heating furnace in an atmospheric environment were performed, the homogenization treatment was carried out under annealing at 900 °C for 5 hours, meanwhile, the part of β phase transformed into α phase, the α-case was formed on the surface and the deeply texture was homogenized simultaneously. Among them, the influence of heat treatment temperature 700 °C - 900 °C atmospheric environment annealing for 5 - 24 hours on the formation of α-case thickness were elucidated. The weight of the sample increased with the increase of temperature and time. The oxidation kinetics of the material were mostly in a parabolic measured through thermogravimetric analysis (TGA), and the thickness of α-case was quantified by utilizing optical microscope (OM), electron probe micro-analyzer (EPMA), and nano-indenter, further to the oxygen diffusion was fitted by Fick's Law, the relationship between the concentration, hardness and depth were established, therefore, the α-case thickness and the diffusion coefficient of oxygen in Ti-1023 under different heat treatment conditions were studied. The experimental results showed that the α-case thickness increased with the increase of heat treatment temperature and time, however, the oxygen diffusion coefficient affected by temperature only. On the other hand, the diffusion of oxygen in Ti-1023 in high temperature atmosphere was also simulated by employing finite element commercial code as well as the average absolute relative error (AARE) 3.67 % verified the oxygen diffusion experimental curve from Fick's Law, the finite element simulation model for estimation of α-case thickness was also constructed in this research. Furthermore, the homogenized Ti-1023 with a 300 μm α-case surface layer (900 °C/5 hrs) was analyzed under different hot compression conditions (700 °C - 900 °C with strain rates 0.01 s-1 - 1 s-1) and deformation strains (20 % - 60 %), the interaction between the existence of α-case on material deformation and crack generation during high temperature compression was clarified. Consequently, the mechanisms of α-case affecting deformation and crack growth were established for all.

[1] Boyer, R. R. (1996). An overview on the use of titanium in the aerospace industry. Materials Science and Engineering: A, 213(1-2), 103-114.
[2] Yin, L., Liang, S., and Zheng, L. (2015). Summary of major factors affecting mechanical properties of TiZr based alloys. World Journal of Engineering.
[3] Shen, J., Chen, B., Umeda, J., Zhang, J., Li, Y., and Kondoh, K. (2019). Rate sensitivity and work-hardening behavior of an advanced Ti-Al-N alloy under uniaxial tensile loading. Materials Science and Engineering: A, 744, 630-637.
[4] Yadav, P., and Saxena, K. K. (2020). Effect of heat-treatment on microstructure and mechanical properties of Ti alloys: An overview. Materials Today: Proceedings, 26, 2546-2557.
[5] Liu, Z., He, B., Lyu, T., and Zou, Y. (2021). A review on additive manufacturing of titanium alloys for aerospace applications: directed energy deposition and beyond Ti-6Al-4V. The Journal of The Minerals, Metals & Materials Society (TMS), 73, 1804-1818.
[6] Williams, J. C., and Boyer, R. R. (2020). Opportunities and issues in the application of titanium alloys for aerospace components. Metals, 10(6), 705.
[7] Cotton, J. D., Briggs, R. D., Boyer, R. R., Tamirisakandala, S., Russo, P., Shchetnikov, N., and Fanning, J. C. (2015). State of the art in beta titanium alloys for airframe applications. The Journal of The Minerals, Metals & Materials Society (TMS), 67(6), 1281-1303.
[8] Aubert and Duval (2019), member of High Performance Alloys Division of Eramet Group, France.
[9] Li, D., Hui, S.X., Ye, W. J., and Li, C. L. (2023). Microstructure and mechanical properties of a new high-strength and high-toughness titanium alloy.Rare Metals volume 42, 281-287.
[10] Jackson, M., Dashwood, R., Flower, H., and Christodoulou, L. (2005). The microstructural evolution of near beta alloy Ti-10V-2Fe-3Al during subtransus forging. Metallurgical and Materials Transactions A, 36, 1317-1327.
[11] Chamanfar, A., Huang, M. F., Pasang, T., Tsukamoto, M., and Misiolek, W. Z. (2020). Microstructure and mechanical properties of laser welded Ti-10V-2Fe-3Al (Ti1023) titanium alloy. Journal of Materials Research and Technology, 9(4), 7721-7731.
[12]凌毓彥，氧原子擴散行為對Ti-6Al-4V表面α-case生成之研究，國立成功大學，機械工程系碩士論文，2001。
[13] Guleryuz, H., and Cimenoglu, H. (2009). Oxidation of Ti-6Al-4V alloy. Journal of Alloys and Compounds, 472(1-2), 241-246.
[14] Okamoto, H. (2011). O-Ti (oxygen-titanium). Journal of Phase Equilibria and Diffusion, 32, 473-474.
[15] Yazdi, R., Ghasemi, H. M., Abedini, M., Wang, C., and Neville, A. (2019). Oxygen diffusion layer on Ti-6Al-4V alloy: scratch and dry wear resistance. Tribology Letters, 67, 1-15.
[16] Sefer, B. (2014). Oxidation and alpha–case phenomena in titanium alloys used in aerospace industry: Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V (Doctoral dissertation, Luleå tekniska universitet).
[17] Gaddam, R., Sefer, B., Pederson, R., and Antti, M. L. (2015). Oxidation and alpha-case formation in Ti-6Al-2Sn-4Zr-2Mo alloy. Materials Characterization, 99, 166-174.
[18] Gardner, H. M., Gopon, P., Magazzeni, C. M., Radecka, A., Fox, K., Rugg, D., Wade, J., Armstrong, D. E. J., Moody, M. P., and Bagot, P. A. J. (2021). Quantifying the effect of oxygen on micro-mechanical properties of a near-alpha titanium alloy. Journal of Materials Research, 1-16.
[19] Rudnytskyj, A., Varga, M., Krenn, S., Vorlaufer, G., Leimhofer, J., Jech, M., and Gachot, C. (2022). Investigating the relationship of hardness and flow stress in metal forming. International Journal of Mechanical Sciences, 232, 107571.
[20] Tiryakioğlu, M. (2015). On the relationship between Vickers hardness and yield stress in Al-Zn-Mg-Cu Alloys. Materials science and engineering: A, 633, 17-19.
[21] Fei, H., Pan, B., Zhang, C., Jiang, Y., Xu, Q., Lu, Y., and Gong, J. (2022). Study on the mechanical properties gradient in surface oxygen diffusion hardened layer of Ti6Al4V alloy. Journal of Materials Research and Technology, 18, 3173-3183.
[22] Kramer, D., Huang, H., Kriese, M., Robach, J., Nelson, J., Wright, A., Bahr, D., and Gerberich, W. W. (1998). Yield strength predictions from the plastic zone around nanocontacts. Acta Materialia, 47(1), 333-343.
[23] Sakharova, N. A., Fernandes, J. V., Antunes, J. M., and Oliveira, M. C. (2009). Comparison between Berkovich, Vickers and conical indentation tests: A three-dimensional numerical simulation study. International Journal of Solids and Structures, 46(5), 1095-1104.
[24] Vaché, N., Cadoret, Y., Dod, B., and Monceau, D. (2021). Modeling the oxidation kinetics of titanium alloys: Review, method and application to Ti-64 and Ti-6242s alloys. Corrosion Science, 178, 109041.
[25] Chang, X., Qi, Y., Chen, X., Xie, Z., Zhang, P., and Chen, G. (2023). Extra work hardening and activation of softening mechanisms induced by α-β interactions of a metastable-β Ti alloy during subtransus processing. Materials Science and Engineering: A, 144653.
[26] Bao, R. Q., Huang, X., and Cao, C. X. (2006). Deformation behavior and mechanisms of Ti-1023 alloy. Transactions of Nonferrous Metals Society of China, 16(2), 274-280.
[27] Wang, K., Lu, S., Fu, M. W., Li, X., and Dong, X. (2009). Optimization of β/near-β forging process parameters of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si by using processing maps. Materials Characterization, 60(6), 492-498.
[28] Momeni, A., and Abbasi, S. M. (2010). Effect of hot working on flow behavior of Ti-6Al-4V alloy in single phase and two phase regions. Materials and Design, 31(8), 3599-3604.
[29] Dong, E., Yu, W., and Cai, Q. (2017). Alpha-case kinetics and high temperature plasticity of Ti-6Al-4V alloy oxidized in different phase regions. Procedia Engineering, 207, 2149-2154.
[30] Zhang, F., Luan, B., Shou, H., Zheng, J., Zhang, X., Liu, R., and Murty, K. L. (2022). A quasi in-situ study on the work hardening and softening mechanisms of Ti-33Zr-12Al-6V alloy. Materials Science and Engineering: A, 835, 142694.
[31] Cerri, E., and Ghio, E. (2020). AlSi10Mg alloy produced by Selective Laser Melting: Relationships between Vickers microhardness, Rockwell hardness and mechanical properties. Metall. Ital, 7-8.
[32] Qiao, Y., Zhang, W., Ran, W., and Guo, X. (2022). Compression deformation behavior of silicide coating on Nb-Si based alloy. Intermetallics, 147, 107615.
[33] Seth, P., Jha, J. S., Alankar, A., and Mishra, S. K. (2022). Alpha-case formation in Ti-6Al-4V in a different oxidizing environment and its effect on tensile and fatigue crack growth behavior. Oxidation of Metals, 97(1-2), 77-95.
[34] Gaddam, R., Antti, M. L., and Pederson, R. (2014). Influence of alpha-case layer on the low cycle fatigue properties of Ti-6Al-2Sn-4Zr-2Mo alloy. Materials Science and Engineering: A, 599, 51-56.
[35] Naydenkin, E. V., Mishin, I. P., Ratochka, I. V., Lykova, O. N., and Zabudchenko, O. V. (2020). The effect of alpha-case formation on plastic deformation and fracture of near β titanium alloy. Materials Science and Engineering: A, 769, 138495.
[36] Longhitano, G. A., Larosa, M. A., Jardini, A. L., de Carvalho Zavaglia, C. A., and Ierardi, M. C. F. (2018). Correlation between microstructures and mechanical properties under tensile and compression tests of heat-treated Ti-6Al-4V ELI alloy produced by additive manufacturing for biomedical applications. Journal of Materials Processing Technology, 252, 202-210.
[37] Zhao, G., Xu, B., Ren, K., Shao, G., and Wang, Y. (2020). Oxygen diffusion through environmental barrier coating materials. Ceramics International, 46(11), 19545-19549.
[38] Fischer-Cripps, A.C. (2011). Nanoindentation Test Standards. In: Nanoindentation. Mechanical Engineering Series. Springer
[39] Duerig, T. W., Terlinde, G. T., and Williams, J. C. (1980). Phase transformations and tensile properties of Ti-10V-2Fe-3AI. Metallurgical Transactions A, 11, 1987-1998.
[40] Claisse, F., and Koenig, H. P. (1956). Thermal and forced diffusion of oxygen in β-titanium. Acta metallurgica, 4(6), 650-654.
[41] Sokiryanskii, L.F., Ignatov, D.V., Shinyaev, A.Ya., Bogolyubova, I.V., Latsh, V.V., and Model, M.S. (1966) (pub. 1968), 201-210 (Ed. N. P. Sazhin, Izd. “Nauka”: Moscow, USSR), from Chemical Abstracts, 1969, vol. 71, no. 8, 83986r.
[42] Carlson, O. N., Schmidt, F. A., and Lichtenberg, R. R. (1975). Investigation of reported anomalies in the electrotransport of interstitial solutes in titanium and iron. Metallurgical Transactions A, 6, 725-731.
[43] Song, M. H., Han, S. M., Min, D. J., Choi, G. S., and Park, J. H. (2008). Diffusion of oxygen in β-titanium. Scripta Materialia, 59(6), 623-626.
[44] Rosa, C. J. (1970). Oxygen diffusion in alpha and beta titanium in the temperature range of 932 to 1142 C. Metallurgical Transactions, 1, 2517-2522.
[45]Askeland, D. R., Phulé, P. P., Wright, W. J., & Bhattacharya, D. K. (2003). The science and engineering of materials.
[46] Seshacharyulu, T., Medeiros, S. C., Frazier, W. G., and Prasad, Y. V. R. K. (2002). Microstructural mechanisms during hot working of commercial grade Ti-6Al-4V with lamellar starting structure. Materials Science and Engineering: A, 325(1-2), 112-125.
[47] Zhang, Z. X., Qu, S. J., Feng, A. H., Shen, J., and Chen, D. L. (2017). Hot deformation behavior of Ti-6Al-4V alloy: Effect of initial microstructure. Journal of Alloys and Compounds, 718, 170-181.
[48] Zhao, Z. L., Liu, N., Xu, W. X., Cao, L. C., Li, S., and Huang, X. Y. (2021). Rapid dynamic transformation in the initial stage of hot deformation of a near alpha titanium alloy. Materials Letters, 305, 130837.
[49] Ozerov, M., Klimova, M., Kolesnikov, A., Stepanov, N., and Zherebtsov, S. (2016). Deformation behavior and microstructure evolution of a Ti/TiB metal-matrix composite during high-temperature compression tests. Materials and Design, 112, 17-26.
[50] Thlrukkonda, M., Srinivasan, R., and Weiss, I. (1994). Instability and flow localization during compression of a flow softening material. Journal of materials engineering and performance, 3(4), 514.
[51] Zhang, W. F., Li, X. L., Sha, W., Yan, W., Wang, W., Shan, Y. Y., and Yang, K. (2014). Hot deformation characteristics of a nitride strengthened martensitic heat resistant steel. Materials Science and Engineering: A, 590, 199-208.
[52] Bustillos, J., and Moridi, A. (2022). Uncovering the deformation pathways of additive manufactured Ti-6Al-4V with engineered duplex microstructure. Materialia, 25, 101545.
[53] Seshacharyulu, T., Medeiros, S. C., Morgan, J. T., Malas, J. C., Frazier, W. G., and Prasad, Y. V. R. K. (2000). Hot deformation and microstructural damage mechanisms in extra-low interstitial (ELI) grade Ti-6Al-4V. Materials Science and Engineering: A, 279(1-2), 289-299.
[54] Tan, Y. B., Duan, J. L., Yang, L. H., Liu, W. C., Zhang, J. W., and Liu, R. P. (2014). Hot deformation behavior of Ti-20Zr-6.5Al-4V alloy in the α+ β and single β phase field. Materials Science and Engineering: A, 609, 226-234.
[55] Li, A. B., Huang, L. J., Meng, Q. Y., Geng, L., and Cui, X. P. (2009). Hot working of Ti-6Al-3Mo-2Zr-0.3 Si alloy with lamellar α+ β starting structure using processing map. Materials and design, 30(5), 1625-1631.
[56] Zhu, Y. C., Zeng, W. D., Liu, J. L., Zhao, Y. Q., Zhou, Y. G., and Yu, H. Q. (2012). Effect of processing parameters on the hot deformation behavior of as-cast TC21 titanium alloy. Materials and Design, 33, 264-272.
[57] Ma, X., Zeng, W., Xu, B., Sun, Y., Xue, C., and Han, Y. (2012). Characterization of the hot deformation behavior of a Ti-22Al-25Nb alloy using processing maps based on the Murty criterion. Intermetallics, 20(1), 1-7.
[58] Zhang, J., Liu, H., Zheng, J., Ji, J., Shi, Y., Jia, L., Yan, Z., Dong, B., and Xue, Y. (2021). Microstructure characterization of hot isostatic pressed Ti-6Al-4V alloy under uniaxial compression and post heat treatment. Journal of Materials Research and Technology, 15, 7070-7084.
[59] Moridi, A., Demir, A. G., Caprio, L., Hart, A. J., Previtali, B., and Colosimo, B. M. (2019). Deformation and failure mechanisms of Ti-6Al-4V as built by selective laser melting. Materials Science and Engineering: A, 768, 138456.
[60] Paliwal, B., and Ramesh, K. T. (2008). An interacting micro-crack damage model for failure of brittle materials under compression. Journal of the Mechanics and Physics of Solids, 56(3), 896-923.
[61] Jiang, Y., Li, Y., Peng, Y., and Gong, J. (2020). Mechanical properties and cracking behavior of low-temperature gaseous carburized austenitic stainless steel. Surface and Coatings Technology, 403, 126343.
[62] Ghosh, A., Sivaprasad, S., Bhattacharjee, A., and Kar, S. K. (2013). Microstructure-fracture toughness correlation in an aircraft structural component alloy Ti-5Al-5V-5Mo-3Cr. Materials Science and Engineering: A, 568, 61-67.
[63] Feng, X., Liang, Y., Sun, H., and Wang, S. (2021). Effect of Dislocation Slip Mechanism under the Control of Oxygen Concentration in Alpha-Case on Strength and Ductility of TC4 Alloy. Metals, 11(7), 1057.