Journal of Advanced Materials and Technologies

Journal of Advanced Materials and Technologies

The Effect of Withdrawal Rate on the Microstructural Defects of a New Cobalt-nickel Based Directionally Solidified Superalloy

Document Type : Original Reaearch Article

Authors
Fatemeh Abdolmaleki 1
Masumeh Seifollahi 2
Sayed Mahdi Qazi mirsaeid 3
1 MSc Student, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.
2 Assistant Professor, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran‎.
3 MSc, Researcher, Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran, Iran.
10.30501/jamt.2023.396693.1278
Abstract
The microstructure of new cobalt-nickel-based superalloys contains γ´ precipitates. Withdrawal rate and temperature gradient are two important parameters affecting the formation of defects such as segregation, microporosity, and eutectic zones. This research discusses the impacts of the withdrawal rate on these defects. To this end, Bridgman furnace was used for directional growth of the samples under a vacuum at the withdrawal rates of 1.5, 3, and 6 mm/min. Upon increasing the speed of the withdrawal rate mold, segregation of the elements is reduced due to the shorter diffusion time. Co and W elements tend to segregate in the dendritic core while Al, Ti, and Ta tend to segregate in the inter-dendritic regions. Throughout the study, the size of microporosity decreased from 14.3 to 9.5 μm while increasing the withdrawal rate from 1.5 up to 6 mm/min. This decrease in the size of micropores resulted from the lack of melt feeding in the inter-dendritic areas. Moreover, the size of the eutectic zones decreased from 14.6 to 8.9 μm upon increasing the withdrawal rate from 1.5 up to 6 mm/min, mainly due to the smaller melt pools in the final stage of solidification.
Keywords
New Cobalt-Nickel Base
Superalloy
Withdrawal Rate Mold
Eutectic
Microporosity
Segregation Elements
Subjects
  1. Anton, D., & Giamei, A. (1985). Porosity distribution and growth during homogenization in single crystals of a nickel-base superalloy. Materials Science and Engineering, 76, 173-180. https://doi.org/10.1016/0025-5416(85)90091-6
  2. Caldwell, , Fela, F., & Fuchs, G. (2004). The segregation of elements in high-refractory-content single-crystal nickel-based superalloys. JOM, 56, 44-48. https://doi.org/10.1007/s11837-004-0200-9
  3. Ding, X., Mi, T., Xue, F., Zhou, H., & Wang, M. (2014. Microstructure formation in γ–γ′ Co–Al–W–Ti alloys during directional solidification. Journal of Alloys and Compounds, 599, 159-163. https://doi.org/10.1016/j.jallcom.2014.02.068
  4. Lian, Y., Gao, L., Hu, P., Yin, Q., Wang, X., Wen, Z., & Wang, J. (2022). Effect of withdrawal rate on the microstructure and mechanical properties of a novel monocrystalline CoNi-based superalloy. Materials Today Communications, 30, 103053. https://doi.org/10.1016/j.mtcomm.2021.103053
  5. Liu, , Shen, J., Zhang, J., & Lou, L. (2010). Effect of withdrawal rates on microstructure and creep strength of a single crystal superalloy processed by LMC. Journal of Materials Science & Technology, 26(4), 306-310. https://doi.org/10.1016/S1005-0302(10)60050-3
  6. Pandey, P., Makineni, S. K., Samanta, A., Sharma, A., Das, S. M., Nithin, B., Srivastava, C., Singh, A. K., Raabe, D., & Gault, B. (2019). Elemental site occupancy in the L12 A3B ordered intermetallic phase in Co-based superalloys and its influence on the microstructure. Acta Materialia, 163, 140-153. https://doi.org/10.1016/j.actamat.2018.09.049
  7. Rajabi Nejad, S., Seifollahi, M., Abbasi, S. M., & Ghazi Mirsaeed, S. M. (2022). Influence of Withdrawal Rate on As-Cast Microstructure and Stress-Rupture Life of Directionally Solidified Rene80 Superalloy. Journal of Advanced Materials and Processing, 10(2), 29-38. [In Persian] 20.1001.1.2322388.2022.10.2.4.9
  8. Wang, F., Ma, D., Zhang, J., Bogner, S., & Bührig-Polaczek, A. (2014). A high thermal gradient directional solidification method for growing superalloy single crystals. Journal of Materials Processing Technology, 214(12), 3112-3121. https://doi.org/10.1016/j.jmatprotec.2014.07.020
  9. YU, Z.-h., Lin, L., ZHAO, X.-b., ZHANG, W.-g., ZHANG, J., & FU, H.-z. (2010). Effect of solidification rate on MC-type carbide morphology in single crystal Ni-base superalloy AM3. Transactions of Nonferrous Metals Society of China, 20(10), 1835-1840. https://doi.org/10.1016/S1003-6326(09)60382-4
  10. Yue, Q., Liu, L., Yang, W., Huang, T., Zhang, J., Fu, H., & Zhao, X. (2017). Influence of withdrawal rate on the porosity in a third-generation Ni-based single crystal superalloy. Progress in Natural Science: Materials International, 27(2), 236-243. https://doi.org/10.1016/j.pnsc.2017.02.008
  11. Zhou, X., Fu, H., Xue, F., Zhang, Y., & Xie, J. (2020). Abnormal precipitation of the μ phase during solution treatment of γ′-strengthened Co-Ni-Al-W-based superalloys. Scripta Materialia, 181, 30-34. https://doi.org/10.1016/j.scriptamat.2020.02.010
  12. Zhuhuan, Y., Lin, L., Xinbao, Z., Weiguo, Z., Jun, Z., & Hengzhi, F. (2010). Effect of solidification parameters on the microstructures of a single crystal Ni-based superalloy AM3. China Foundry, 7(3), 217-223.‏ 1016/j.proeng.2011.12.570

 

Journal of Advanced Materials and Technologies
Volume 12, Issue 4
Winter 2024
Pages 15-23

  • Receive Date 21 June 2023
  • Revise Date 21 August 2023
  • Accept Date 05 September 2023