TERMOMEKANİK İŞLEMİN (Co25Cr15Fe20Ni40)83Al17 YÜKSEK ENTROPİLİ ALAŞIMININ MİKROYAPISINA VE SERTLİĞİNE ETKİSİ

Yıl 2023, , 501 - 508, 29.04.2023

Hüseyin Burak Kocabaş , Akın Özcan , G. İpek Selimoğlu , Hakan Gaşan

https://doi.org/10.31796/ogummf.1128421

Öz

(Co25Cr15Fe20Ni40)83Al17 yüzey merkezli kübik (FCC) ve hacim merkezli kübik (BCC) fazlardan oluşan bir ötektik yüksek entropili alaşımdır (EYEA). Bu ikili faz karışımı (FCC+BCC), iyi süneklik ve mukavemet kombinasyonu sağlar. Bu çalışma kapsamında, vakum ark ergitme ve döküm yöntemi ile üretilen (Co25Cr15Fe20Ni40)83Al17 EYEA'nın mikroyapısı ve sertliği üzerine mekanik, termal ve termomekanik süreçlerin etkisinin incelenmesi amaçlanmıştır. Bu amaçla, döküm levhalara soğuk ve sıcak haddeleme ile farklı tavlama işlemleri uygulanmıştır. Soğuk haddeleme oda sıcaklığında yapılırken, sıcak haddeleme sıcaklığı 500-1000℃ arasında değiştirilmiştir. Soğuk ve sıcak haddeleme sonrasında uygulanabilen maksimum deformasyon sırasıyla %50 ve %60 olmuştur. Sınırlı deforme edilebilirlik, uygulanan deformasyonla ötektik faz karışımında artan BCC/B2 oranına bağlanmıştır. %50 soğuk haddelemeden sonra sertlik 280 HV'den 412 HV'ye yükselmiştir. Benzer yüksek sertlik değeri (399 HV) 750℃'de ~%50 deformasyondan sonra elde edilmiştir ki bu da dinamik yeniden kristalleşmenin 1000 ℃'ye kadar belirgin bir etkisinin olmadığını göstermektedir.

Anahtar Kelimeler

Ötektik Yüksek Entropili Alaşım, Vakum Ark Ergitme, Haddeleme, Tavlama

THE EFFECT OF THE THERMOMECHANICAL PROCESSING ON THE MICROSTRUCTURE AND HARDNESS OF (Co25Cr15Fe20Ni40)83Al17 HIGH ENTROPY ALLOY

Öz

(Co25Cr15Fe20Ni40)83Al17 is a eutectic high entropy alloy (EHEA), which is composed of face centered cubic (FCC) and body centered cubic (BCC) phases. This dual (FCC+BCC) phase mixture provides good ductility and strength combination. In the scope of this study, it was aimed to analyze the effect of mechanical, thermal and thermomechanical processes on the microstructure and hardness of (Co25Cr15Fe20Ni40)83Al17 EHEA, which was produced by the vacuum arc melting and casting method. With this aim, cold and hot rolling as well as different annealing treatments were applied to the as-cast plates. The cold-rolling was performed at room temperature while the hot rolling temperature was varied in between 500-1000℃. The maximum deformation that can be applied was 50% and 60 % after cold and hot rolling, respectively. The limited deformability was attributed to the increased BCC/B2 content in the eutectic phase mixture with the applied deformation. The hardness was increased from 280 HV to 412 HV after 50% cold-rolling. A similar high hardness value (399 HV) was obtained after ~50% deformation at 750℃, indicating that the dynamic recrystallization had no significant effect up to 1000℃.

Anahtar Kelimeler

Eutectic High Entropy Alloy, Vacuum Arc Melting, Rolling, Annealing

Kaynakça

• Bhattacharjee, T., Wani, I. S., Sheikh, S., Clark, I. T., Okawa, T., Guo, S., Bhattacharjee S. & Tsuji, N. (2018). Simultaneous strength-ductility enhancement of a nano-lamellar AlCoCrFeNi2.1 eutectic high entropy alloy by cryo-rolling and annealing. Scientific Reports, 8 (3276). doi : http://dx.doi.org/10.1038/s41598-018-21385-y
• Hemphill, M. A., Yuan, T., Wang, G. Y., Yeh, J. W., Tsai, C. W., Chuang, A. & Liaw, P. K. (2012). Fatigue behavior of Al0.5CoCrCuFeNi high entropy alloys. Acta Materialia, 60 (16), 5723–5734. doi: https://doi.org/10.1016/j.actamat.2012.06.046
• Pickering, E. J. & Jones, N. G. (2016). High-entropy alloys: A critical assessment of their founding principles and future prospects. International Materials Reviews, 61(3), 183-202. doi: https://doi.org/10.1080/09506608.2016.1180020
• Reddy, S.R., Yoshida, S., Sunkari, U., Lozinko, A., Joseph, J., Saha, R., Fabijanic, D., Guo, S., Bhattacharjee, P.P., Tsuji, N. (2019). Engineering heterogeneous microstructure by severe warm-rolling for enhancing strength-ductility synergy in eutectic high entropy alloys. Materials Science & Engineering A, 764, 138226. doi: https://doi.org/10.1016/j.msea.2019.138226
• Senkov, O.N., Wilks, G.B., Scott, J.M., Miracle, D.B. (2011). Mechanical properties of Nb25Mo25Ta25W25 and V20Nb20Mo20Ta20W20 refractory high entropy alloys. Intermetallics, 19 (5), 698-706. doi: https://doi.org/10.1016/j.intermet.2011.01.004
• Tian, Q., Zhang, G., Yin, K. Wang, L., Wang, W., Cheng, W., Wang, Y., Huang, J.C. (2020). High temperature deformation mechanism and microstructural evolution of relatively lightweight AlCoCrFeNi high entropy alloy. Intermetallics, 119, 106707. doi: https://doi.org/10.1016/j.intermet.2020.106707
• Tong, C.J., Chen, M.R., Yeh, J.W. , Lin,S.J., Chen,S-K., Shun, T-T. & Chang,S-Y. (2005).Mechanical performance of the Al x CoCrCuFeNi high-entropy alloy system with multiprincipal elements. Metallurgical and Materials Transactions A, 36A, 1263–1271. doi: https://doi.org/10.1007/s11661-005-0218-9
• Wani, I.S., Bhattacharjee,T., Sheikh,S., Lu,Y., Chatterjee, S., Guo, S. Bhattacharjee, P.P, Tsuji,N. (2017). Effect of severe cold-rolling and annealing on microstructure and mechanical properties of AlCoCrFeNi2.1 eutectic high entropy alloy. IOP Conf. Series: Materials Science and Engineering, 194, 012018. doi: http://dx.doi.org/10.1088/1757-899X/194/1/012018
• Yiping, L., Yong, D., Sheng, G., Li, J., Huijun, K., Tongmin, W., Bin, W., Zhijun, W., Jinchuan, J., Zhiqiang, C., Haihui, R. & Tingju, L. (2014). A promising new class of high temperature alloys: Eutectic high-entropy alloys. Scientific Reports, 4 (6200). doi: http://dx.doi.org/10.1038/srep06200