بررسی تأثیر عملیات همگن‌سازی بر توزیع عناصر آلیاژی، ریزساختار و سختی سوپرآلیاژ بر پایه ترکیب Co-Al-W-Ti-Ta

نویسندگان

دانشگاه صنعتی مالک اشتر، تهران، ایران

چکیده

هدف از انجام این پژوهش، بررسی تأثیر دما و زمان عملیات همگن‌سازی بر ریزساختار، توزیع عناصر آلیاژی و سختی سوپرآلیاژ پایه کبالت نسل جدید با ترکیب Co-7Al-7W-4Ti-2Ta است. به این منظور نمونه‌ها تحت عملیات همگن‌سازی در دو دمای 1250 و 1300 درجه سانتی‌گراد طی زمان‌های 2، 4، 6 و 8 ساعت قرار گرفته و سپس در آب سرد شدند. در ادامه نمونه‌ها تحت بررسی‌های ریزساختاری به‌وسیله میکروسکوپ نوری و الکترونی و سختی‌سنجی قرار گرفتند. نتایج نشان داد که با افزایش دمای عملیات همگن‌سازی تا 1300 درجه سانتی‌گراد، تخلخل حاصل از اکسیداسیون تیتانیم به‌همراه ذوب موضعی ترکیب‌های یوتکتیکی حاوی Al-Co-Ti، منجربه کاهش سختی تا 90 ویکرز شده است. این پدیده به‌علت جدایش زیاد عناصر آلیاژی در ساختار ریختگی است که با ذوب مجدد آلیاژ از شدت و آثار مخرب این جدایش کاسته شد. اما با همگن‌سازی در دمای 1250 درجه سانتی‌گراد ذوب موضعی مناطق یوتکتیک یا تخلخل در نمونه‌ها مشاهده نشد و با افزایش زمان ساختار یکنواخت‌تری حاصل شده است. حداقل و حداکثر سختی حاصل شده پس از همگن‌سازی در دمای 1250 درجه سانتی‌گراد به‌ترتیب 348 و 406 ویکرز به‌دست آمد. همچنین در این دما با افزایش زمان عملیات همگن‌سازی ساختار یکنواخت‌تری حاصل شده است.

کلیدواژه‌ها

عنوان مقاله [English]

Investigation of the Effect of Homogenization Treatment on Distribution of Alloying Elements, Microstructure and Hardness of Co-Al-W-Ti-Ta-Base Superalloy

نویسندگان [English]

  • M. Etminan
  • M. Morakabati
  • S. M. Qazi mir saeid
Malek Ashtar University, Tehran, Iran.
چکیده [English]

The aim of this study was to investigate the effect of temperature and time of homogenization treatment on the microstructure, distribution of alloying elements and hardness of the novel Co-based superalloy Co-7Al-7W-4Ti-2Ta. For this purpose, the specimens were first homogenized at 1250 and 1300 °C for 2, 4, 6 and 8 hours and then water-cooled. Subsequently, the specimens were subjected to hardness testing and microstructural examinations by optical and electron microscopy. The results showed that by increasing the homogenization temperature to 1300 °C, the porosity created by Ti oxidation and local melting of the Co-Al-Ti eutectic compounds led to a decrease in hardness to 90 Vickers. This phenomenon was due to high segregation of alloying elements in the cast structure. The intensity and destructive effects of this segregation were reduced by remelting of alloy. However, by homogenization at 1250 °C, no local melting of eutectic zones or porosity were observed in the specimens and a more uniform structure was obtained with increasing time. Minimum and maximum hardness values after homogenization at 1250°C were 348 and 406 Vickers, respectively. Moreover, the microstructure became more homogenous by increasing the homogenization treatment time at this temperature.

کلیدواژه‌ها [English]

  • Novel co-based superalloy
  • Homogenization treatment
  • microstructure
  • Hardness

مراجع

1. Gu, Y., Harada, H., Cui, C., Ping, D., Sato, A., and Fujioka, J., “New Ni-Co-Base Disk Superalloys with Higher Strength and Creep resistance”, Scripta Materialia, Vol. 9, pp. 815-818, 2006.
2. Bocchini, P. J., “Microstructure and Mechanical Properties in Gamma (Face-Centered Cubic) + Gamma Prime (L12) Precipitation-Strengthened Cobalt-based Superalloys”, Ph.D. Thesis, Northwestern University, 2015.
3. Yan, H -Y., Vorontsov, V. A., and Dye, D., “Alloying Effects in Polycrystalline γ′ Strengthened Co-Al-W Base Alloys”, Intermetallics, Vol. 48, pp. 44-53, 2014.
4. Bauer, A., Neumeier, S., Pyczak, F., and Göken, M., “Microstructure and Creep Strength of different γ/γ′-Strengthened Co-Base Superalloy variants”, Scripta Materialia, Vol. 12, pp. 1197-1200, 2010.
5. Bauer, A., Neumeier, S., Pyczak, F., Singer R. F., and Göken, M., “Creep Properties of Different γ′-Strengthened Co-Base Superalloys”, Materials Science and Engineering, Vol. 550, pp. 333-341, 2012.
6. Zhu, L., Wei, C., Qi, H., Jiang, L., Jin, Z., and Zhao, J. -C., “Experimental Investigation of Phase Equilibria in the Co-Rich Part of the Co-Al-X (X= W, Mo, Nb, Ni, Ta) Ternary Systems using Diffusion Multiples”, Journal of Alloys and Compounds, Vol. 691, pp. 110-118, 2017.
7. Ding, X. F., Mi, T., Xue, F., Zhou, H. J., and Wang, M. L., “Microstructure Formation in γ–γ′ Co-Al-W-Ti Alloys During Directional Solidification”, Journal of Alloys and Compounds, Vol. 599, pp. 159-163, 2014.
8. McDevitt, E. T., “Feasibility of Cast and Wrought Co-Al-WX Gamma-prime Superalloys”, Materials Science Forum, Trans Tech Publications, Vol. 783, Pp. 1159-1164, 2014.
9. Mughrabi, H., “The Importance of Sign and Magnitude of γ/γ′ Lattice Misfit in Superalloys-with Special Reference to the New γ′-Hardened Cobalt-Base Superalloys”, Acta Materialia, Vol. 81, pp. 21-29, 2014.
10. Xue, F., Zhou, H., Chen, X., Shi, Q., Chang, H., Wang, M., Ding, X. and Feng, Q., “Creep Behavior of a Novel Co-Al-W-Base Single Crystal Alloy Containing Ta and Ti at 982 ∘C”, MATEC Web of Conferences, EDP Sciences, Vol. 14, p. 15002, 2014.
11. Zhuang, X., Song L., Longfei, L., and Qiang, F., “Microstructures and Properties of a Novel
γ′-Strengthened Multi-Component CoNi-Based Wrought Superalloy Designed by CALPHAD Method”, Materials Science and Engineering, pp. 139-219, 2020.
12. Hausmann, D., Solís, C., Freund, L. P., Volz, N., Heinemann, A., Göken, M., Gilles, R., and Neumeier, S., “Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the g/g¢ Microstructure”, Metals, Vol. 3, pp. 321, 2020.
13. Sohrabi, M. J., and Mirzadeh, H. “Estimation of Homogenisation Time for Superalloys Based on a New Diffusional Model”, Materials Science and Technology 36, Vol. 3, pp. 380-384, 2020.
14. Povstugar, I., Choi, P -Pa., Neumeier, S., Bauer, A., Zenk, C. H., Göken, M., and Raabe, D., “Elemental Partitioning and Mechanical Properties of Ti- and Ta-Containing Co-Al-W-Base Superalloys Studied by Atom Probe Tomography and Nanoindentation”, Acta Materialia, Vol. 78, pp. 78-85, 2014.
15. Casas, R., Gálvez, F., and Campos, M., “Microstructural Development of Powder Metallurgy Cobalt-Based Superalloys Processed by Field Assisted Sintering Techniques (FAST)”, Materials Science and Engineering, Vol. 724, pp. 461-468, 2018.
16. Zhou, X., Fu, H., Zhang, Y., Xu, H., and Xie, J., “Effect of Ta and Ti on the Solidification Characteristics of Novel γ′-Strengthened Co-base Superalloys”, Journal of Alloys and Compounds, Vol. 768, pp. 464-475, 2018.
مواد پیشرفته در مهندسی
دوره 39، شماره 2
شهریور 1399
صفحه 103-119

فایل ها

هم رسانی

ارجاع به این مقاله

آمار

تحت نظارت وف ایرانی