Characterization and Modeling of NbNiTaTiW and NbNiTaTiW-Al Refractory High-Entropy Alloys


High-entropy alloys (HEAs) represent a new class of material that exhibit unique materials properties and complex microstructure. Little work to date has been done on refractory HEAs (RHEAs), which can loosely be defined as an HEA with the majority of the alloy being refractory metals. In this study, the authors examined two unique RHEA systems: (1) Nb20Ni20Ta20Ti20W20 and (2) Nb18Ni18Ta18Ti18W18Al10. The RHEAs were characterized in the as-cast and heat-treated condition using scanning electron microscopy equipped with energy dispersive spectroscopy to observe the microstructural evolution and elemental segregation and X-ray diffraction to determine the number of phases present and their crystal structure. The RHEA mechanical properties were tested via Vickers hardness measurements. Thermodynamic simulations of the solidification process were performed using a CALPHAD approach involving two basic models: equilibrium lever rule and non-equilibrium Scheil-Gulliver. The simulations were compared with the experimental data.

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  1. 1.

    Zhang Y, Zuo TT, Tang Z, Gao MC, Dahmen KA, Liaw PK, Lu ZP (2014) Progress in Materials Science 61:1–93.

    Article  Google Scholar 

  2. 2.

    Dobbelstein H, Thiele M, Gurevich EL, George EP, Ostendorf A (2016) Physics Procedia 83:624–633.

    CAS  Article  Google Scholar 

  3. 3.

    Otto F, Dlouhý A, Pradeep KG, Kuběnová M, Raabe D, Eggeler G, George EP (2016) Acta Mater. 112:40–52.

    CAS  Article  Google Scholar 

  4. 4.

    Gorsse S, Miracle DB, Senkov ON (2017) Acta Mater. 135:177–187.

    CAS  Article  Google Scholar 

  5. 5.

    Gorsse S, Couzinié J-P, Miracle DB (2018) C. R. Physique 19:721-736.

    CAS  Article  Google Scholar 

  6. 6.

    J. W. Yeh, S. K. Chen, S. J. Lin, J. Y. Gan, T. S. Chin, T. T. Shun, C. H. Tsau and S. Y. Chang, Advanced Engineering Materials 2004, vol. 6, pp. 299-303.

    CAS  Article  Google Scholar 

  7. 7.

    K. B. Zhang, Z. Y. Fu, J. Y. Zhang, W. M. Wang, H. Wang, Y. C. Wang, Q. J. Zhang and J. Shi, Materials Science and Engineering: A 2009, vol. 508, pp. 214-219.

    Article  Google Scholar 

  8. 8.

    Woei-Ren Wang, Wei-Lin Wang and Jien-Wei Yeh, Journal of Alloys and Compounds 2014, vol. 589, pp. 143-152.

    CAS  Article  Google Scholar 

  9. 9.

    Daniel Miracle, Jonathan Miller, Oleg Senkov, Christopher Woodward, Michael Uchic and Jaimie Tiley, Entropy 2014, vol. 16, pp. 494-525.

    CAS  Article  Google Scholar 

  10. 10.

    O. N. Senkov and D. B. Miracle, Journal of Alloys and Compounds 2016, vol. 658, pp. 603-607.

    CAS  Article  Google Scholar 

  11. 11.

    S. Varalakshmi, M. Kamaraj and B. S. Murty, Journal of Alloys and Compounds 2008, vol. 460, pp. 253-257.

    CAS  Article  Google Scholar 

  12. 12.

    Yong Zhang, Jien-Wei Yeh, Jian F. Sun, Jun P. Lin and Ke-Fu Yao, Advances in Materials Science and Engineering 2015, vol. 2015, pp. 1-1.

    Google Scholar 

  13. 13.

    Y. Zhang, S. G. Ma and J. W. Qiao, Metallurgical and Materials Transactions A 2011, vol. 43, pp. 2625-2630.

    Google Scholar 

  14. 14.

    X. Yang and Y. Zhang, Materials Chemistry and Physics 2012, vol. 132, pp. 233-238.

    CAS  Article  Google Scholar 

  15. 15.

    B. S. Li, Y. P. Wang, M. X. Ren, C. Yang and H. Z. Fu, Materials Science and Engineering: A 2008, vol. 498, pp. 482-486.

    Article  Google Scholar 

  16. 16.

    K. Y. Tsai, M. H. Tsai and J. W. Yeh, Acta Mater. 2013, vol. 61, pp. 4887-4897.

    CAS  Article  Google Scholar 

  17. 17.

    ON Senkov, GB Wilks, DB Miracle, CP Chuang and PK Liaw, Intermetallics 2010, vol. 18, pp. 1758-1765.

    CAS  Article  Google Scholar 

  18. 18.

    O. N. Senkov, G. B. Wilks, J. M. Scott and D. B. Miracle, Intermetallics 2011, vol. 19, pp. 698-706.

    CAS  Article  Google Scholar 

  19. 19.

    ON Senkov, JM Scott, SV Senkova, DB Miracle and CF Woodward, Journal of alloys and compounds 2011, vol. 509, pp. 6043-6048.

    CAS  Article  Google Scholar 

  20. 20.

    RS Mishra, N Kumar and M Komarasamy, Materials Science and Technology 2015, vol. 31, pp. 1259-1263.

    CAS  Article  Google Scholar 

  21. 21.

    Daniel B Miracle and Oleg N Senkov, Acta Mater. 2017, vol. 122, pp. 448-511.

    CAS  Article  Google Scholar 

  22. 22.

    Soni V, Senkov ON, Gwalani B, Miracle DB, Banerjee R (2018) Sci. Rep. 8:8816

    CAS  Article  Google Scholar 

  23. 23.

    O. N. Senkov, S. V. Senkova and C. Woodward, Acta Mater. 2014, vol. 68, pp. 214-228.

    CAS  Article  Google Scholar 

  24. 24.

    Erich Scheil, Zeitschrift für Metallkunde 1942, vol. 34, pp. 70-72.

    Google Scholar 

  25. 25.

    GH Gulliver, J. Inst. Met 1913, vol. 9, pp. 120-157.

    Google Scholar 

  26. 26.

    Chuan Zhang, Fan Zhang, Shuanglin Chen and Weisheng Cao, JOM 2012, vol. 64, pp. 839-845.

    CAS  Article  Google Scholar 

  27. 27.

    B Zhang, MC Gao, Y Zhang, S Yang and SM Guo, Materials Science and Technology 2015, vol. 31, pp. 1207-1213.

    CAS  Article  Google Scholar 

  28. 28.

    B Zhang, MC Gao, Y Zhang and SM Guo, Calphad 2015, vol. 51, pp. 193-201.

    CAS  Article  Google Scholar 

  29. 29.

    ON Senkov, JD Miller, DB Miracle, C Woodward (2015) Nat Commun 85:1404

    CAS  Article  Google Scholar 

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The authors thank the Forging Industry Association’s FIERF program for partial support of this research. Nathan Ley thanks the AFRL/RWMWS Munitions-Eglin program for partial support of this research. The authors especially thank Dr. Dan Miracle of AFRL AFRL/RX Materials-Dayton for providing his insight and extensive knowledge on the subject of HEAs/CCAs. The authors thank Richard Harris, Dr. Sean Gibbons, and Dr. Rachel Abrahams for their help with characterization as well as for access to facilities and equipment for Nathan Ley at AFRL/RWMWS Munitions-Eglin. The authors acknowledge UNT’s Materials Research Facility (MRF) for providing access to equipment. Stéphane Gorsse thanks Thermo-Calc Software AB for providing the TCHEA databases.

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Correspondence to Nathan A. Ley.

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Manuscript submitted November 26, 2018.

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Ley, N.A., Segovia, S., Gorsse, S. et al. Characterization and Modeling of NbNiTaTiW and NbNiTaTiW-Al Refractory High-Entropy Alloys. Metall Mater Trans A 50, 4867–4876 (2019).

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