Fabrication, Properties of Dense CA₆ Refractory and Its Reaction Behavior with Titanium Aluminum Alloy

Abstract

The key objective in the production of titanium-aluminum alloys by vacuum induction melting technology is to develop crucible materials with excellent thermal stability and thermal shock resistance. In this work, a dense CA₆ (calcium hexaluminate) refractory material was successfully prepared by a two-step sintering method using industrial Al₂O₃ and CaCO₃ as raw materials. The properties of CA₆ refractory and its refaction behavior with Ti6Al4V alloy were investigated, by setting Al₂O₃ and CA₆-Al₂O₃ materials as control groups. The CA₆ refractory showed the highest flexural strength and medium thermal shock resistance. By comparing the reaction behavior of different crucibles with Ti6Al4V alloy, the pure CA₆ crucible showed the best resistance to alloy corrosion. It was almost not eroded after melting (only~100 μm of penetration was observed), and the alloy was the least polluted. Based on the excellent chemical stability and thermal shock resistance of CA₆, it could be a potential titanium aluminum alloy smelting material.

Keywords

CA₆ / Titanium aluminum alloy / Reaction interface / Chemical stability

Acknowledgements

The authors are thankful for the financially support from the National Natural Science Foundation of China (Grant Nos. 52472032 and 52172023), the Key Program of Natural Science Foundation of Hubei Province (Grant No. 2024AFA083) and the Research Project of Hubei Provincial Department of Science and Technology (Grant No. 2024CSA075).

Author Contributions

Conceptualization, L.F. and H.G.; Methodology, L.F.; Software, S.H.; Validation, S.H. and N.L.; Formal Analysis, S.H.; Investigation, S.H.; Resources, J.Z.; Data Curation, S.H.; Writing—Original Draft Preparation, S.H.; Writing—Review & Editing, L.F., C.P., N.L., H.G., J.Z. and A.H.; Visualization, S.H.; Supervision, L.F.; Project Administration, L.F.; Funding Acquisition, L.F.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data are available from the corresponding author on reasonable request.

Funding

This research was funded by the National Natural Science Foundation of China (Grant Nos. 52472032 and 52172023), the Key Program of Natural Science Foundation of Hubei Province (Grant No. 2024AFA083) and the Research Project of Hubei Provincial Department of Science and Technology (Grant No. 2024CSA075).

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

[1] Rack H, Qazi J.Titanium alloys for biomedical applications. Mater. Sci. Eng. C 2006, 26, 1269-1277. doi:10.1016/j.msec.2005.08.032.

[2] Leyens C, Peters M. Titanium and Titanium Alloys: Fundamentals and Applications; Wiley‐VCH: Weinheim, Germany, 2006. doi:10.1002/3527602119.

[3] Luo S, Wang Q, Zhang P, Li J, Liu Q. Effect of friction conditions on phase transformation characteristics in hot forging process of Ti-6Al-4V turbine blade. J. Mater. Res. Technol. 2020, 9, 2107-2115. doi:10.1016/j.jmrt.2019.12.041.

[4] Pan W, Huang D, Wang W, Dou G, Lyu P. Recent Advances in High-Temperature Properties of High-Entropy Alloys. High-Temp. Mater. 2025, 2, 10011. doi:10.70322/htm.2025.10011.

[5] Duan B, Yang Y, He S, Feng Q, Mao L, Zhang X, et al. History and development of γ-TiAl alloys and the effect of alloying elements on their phase transformations. J. Alloys Compd. 2022, 909, 164811. doi:10.1016/j.jallcom.2022.164811.

[6] Liu C, Wang Y, Han W, Ma T, Ma D, Zhang Y. Achieving superior high-temperature strength and oxidation resistance of TiAl nanocomposite through in situ semicoherent MAX phase precipitation. ACS Appl. Mater. Interfaces 2022, 14, 8394-8403. doi:10.1021/acsami.1c21719.

[7] Kagerer S, Hudak OE, Wojcik T, Hahn R, Davydok A, Schloffer M, et al. Oxidation protection of TNM alloys with Al-rich γ-TiAl-based coatings. J. Alloys Compd. 2023, 969, 172343. doi:10.1016/j.jallcom.2023.172343.

[8] Fang ZZ, Paramore JD, Sun P, Chandran KR, Zhang Y, Xia Y, et al. Powder metallurgy of titanium—Past, present, and future. Int. Mater. Rev. 2018, 63, 407-459. doi:10.1080/09506608.2017.1366003.

[9] Feng Q, Deng S, Liao H, Liu C, Gao P, Wang E, et al. Erosion Resistance of BaZrO₃-Y₂O₃ Two-Phase Crucibles against Highly Active Ti2Ni Alloys. High-Temp. Mater. 2024, 1, 10003. doi:10.35534/htm.2024.10003.

[10] Wang J, Kong L, Li T, Xiong T. A novel TiAl₃/Al₂O₃ composite coating on γ-TiAl alloy and evaluating the oxidation performance. Appl. Surf. Sci. 2016, 361, 90-94. doi:10.1016/j.apsusc.2015.11.155.

[11] Fashu S, Lototskyy M, Davids MW, Pickering L, Linkov V, Tai S, et al. A review on crucibles for induction melting of titanium alloys. Mater. Des. 2020, 186, 108295. doi:10.1016/j.matdes.2019.108295.

[12] Wei J, Han B, Wang X, Chen J, Wei Y, Yan W, et al. Improvement in hydration resistance of CaO granules based on CaO-TiO₂, CaO-ZrO₂ and CaO-V₂O₅ systems. Mater. Chem. Phys. 2020, 254, 123413. doi:10.1016/j.matchemphys.2020.123413.

[13] Tetsui T, Kobayashi T, Kishimoto A, Harada H. Structural optimization of an yttria crucible for melting TiAl alloy. Intermetallics 2012, 20, 16-23. doi:10.1016/j.intermet.2011.08.026.

[14] Chen YF, Xiao SL, Tian J, Xu LJ, Chen YY. Effect of particle size distribution on properties of zirconia ceramic mould for TiAl investment casting. Trans. Nonferrous Met. Soc. China 2011, 21, s342-s347. doi:10.1016/S1003-6326(11)61603-8.

[15] Eatesami D, Hadavi MM, Habibollahzade A. Melting of γ-TiAl in the alumina crucible. Russ. J. Non-Ferr. Met. 2009, 50, 363-367. doi:10.3103/S1067821209040105.

[16] Li Z, Fu L, Gu H, Or SW, Huang A, Lv R. Fabrication of in-situ Ti(C,N) phase toughened Al₂O₃ based ceramics from natural bauxite. Ceram. Int. 2021, 47, 25497-25504. doi:10.1016/j.ceramint.2021.05.273.

[17] Zhang H, Tang X, Zhou C, Zhang H, Zhang S. Comparison of directional solidification of γ-TiAl alloys in conventional Al₂O₃ and novel Y₂O₃-coated Al₂O₃ crucibles. J. Eur. Ceram. Soc. 2013, 33, 925-934. doi:10.1016/j.jeurceramsoc.2012.11.006.

[18] Zhu J, Kamiya A, Yamada T, Shi W, Naganuma K, Mukai K. Surface tension, wettability and reactivity of molten titanium in Ti/yttria-stabilized zirconia system. Mater. Sci. Eng. A 2002, 327, 117-127. doi:10.1016/S0921-5093(01)01732-4.

[19] Fu BG, Wang HW, Zou CM, Ma P, Wei ZJ. Interfacial reactions between Ti-1100 alloy and CaO crucible during casting process. Trans. Nonferrous Met. Soc. China 2014, 24, 3118-3125. doi:10.1016/S1003-6326(14)63450-6.

[20] Tetsui T, Kobayashi T, Mori T, Kishimoto T, Harada H. Evaluation of Yttria Applicability as a Crucible for Induction Melting of TiAl Alloy. Mater. Trans. 2010, 51, 1656-1662. doi:10.2320/matertrans.MAW201002.

[21] Salomão R, Ferreira VL, de Oliveira IR, Souza ADV, Correr WR. Mechanism of pore generation in calcium hexaluminate (CA₆) ceramics formed in situ from calcined alumina and calcium carbonate aggregates. J. Eur. Ceram. Soc. 2016, 36, 4225-4235. doi:10.1016/j.jeurceramsoc.2016.05.026.

[22] Cui S, Wang Q, Zhou Y, Mao D, Bao J, Song X. Effect of nickel oxide and titanium oxide on the microstructural, optical, and mechanical properties of calcium hexaaluminate ceramics. Ceram. Int. 2021, 47, 35302-35311. doi:10.1016/j.ceramint.2021.09.073.

[23] Salomão R, Ferreira VL, Costa LMM, de Oliveira IR. Effects of the initial CaO-Al₂O₃ ratio on the microstructure development and mechanical properties of porous calcium hexaluminate. Ceram. Int. 2018, 44, 2626-2631. doi:10.1016/j.ceramint.2017.11.010.

[24] Liu J, Gu H, Zhang M, Huang A, Li H. Improvement in fatigue resistance performance of corundum castables with addition of different size calcium hexaluminate particles. Ceram. Int. 2019, 45, 225-232. doi:10.1016/j.ceramint.2018.09.155.

[25] Qi X, Fu L, Du R, Gu H, Chen D, Yang S, et al. Properties of various CaO-Al₂O₃-TiO₂ refractories and their reaction behaviours in contact with Ti6Al4V melts. J. Alloy Compd. 2023, 959, 170599. doi:10.1016/j.jallcom.2023.170599.