AlCoCrFeNi is among the promising high-entropy alloys (HEAs) that possess high strength with considerable ductility. Powder sintering is one of the competitive routes for the production of HEA powders. However, sintering of HEA powders under a pressureless condition is difficult. The present work aims to produce high-density components from mechanically alloyed AlCoCrFeNi HEA powders through the pressureless sintering method. Nearly full density was achieved at 1275 °C. Sintering was performed in the presence of a viscous phase in the temperature range of 1200–1250 °C, which was confirmed through differential scanning calorimetry and dilatometric measurements. This viscous phase was found have a Cr-rich composition, detected by interrupting the sintering and quenching of the sample. The powder initially contained the BCC phase with a small fraction of FCC and other phases. During sintering, a significant fraction of the FCC phase and nanosized B2 phase were formed. Sintered sample had a hardness of 679 ± 20 Hv.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
D.B. Miracle and O.N. Senkov: A critical review of high entropy alloys and related concepts. Acta Mater. 122, 448 (2017).
M.C. Gao, J.W. Yeh, P.K. Liaw, and Y. Zhang: High-Entropy Alloys (Springer, Cham, 2016).
B. Cantor, I.T.H. Chang, P. Knight, and A.J.B. Vincent: Microstructural development in equiatomic multicomponent alloys. Mater. Sci. Eng., A 375, 213 (2004).
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: Nanostructured high-entropy alloys with multiple principal elements: Novel alloy design concepts and outcomes. Adv. Eng. Mater. 6, 299 (2004).
S. Ranganathan: Alloyed pleasures: Multimetallic cocktails. Curr. Sci. 85, 1404 (2003).
O.N. Senkov, D.B. Miracle, K.J. Chaput, and J.P. Couzinie: Development and exploration of refractory high entropy alloys—A review. J. Mater. Res. 33, 1 (2018).
Y. Lu, Y. Dong, S. Guo, L. Jiang, H. Kang, T. Wang, B. Wen, Z. Wang, J. Jie, Z. Cao, H. Ruan, and L. Tingju: A promising new class of high-temperature alloys: Eutectic high-entropy alloys. Sci. Rep. 4, 6200 (2014).
Y. Zhang, T.T. Zuo, Z. Tang, M.C. Gao, K.A. Dahmen, P.K. Liaw, and Z.P. Lu: Microstructures and properties of high-entropy alloys. Prog. Mater. Sci. 61, 1 (2014).
Z. Li, K.G. Pradeep, Y. Deng, D. Raabe, and C.C. Tasan: Metastable high-entropy dual-phase alloys overcome the strength—ductility trade-off. Nature 534, 227 (2016).
S. Singh, N. Wanderka, and B.S. Murty: Decomposition in multi-component AlCoCrCuFeNi high-entropy alloy. Acta Mater. 59, 182 (2011).
C. Chattopadhyay and B.S. Murty: Kinetic modification of the ‘confusion principle’ for metallic glass formation. Scr. Mater. 116, 7 (2016).
D.H. Xiao, P.F. Zhou, W.Q. Wu, H.Y. Diao, M.C. Gao, M. Song, and P.K. Liaw: Microstructure, mechanical and corrosion behaviors of AlCoCuFeNi–(Cr,Ti) high entropy alloys. Mater. Des. 116, 438 (2017).
L. Guo, W. Wu, N. Song, Z. Wang, and M. Song: Effect of annealing on the microstructural evolution and phase transition in an AlCrCuFeNi2 high entropy alloy. Micron 101, 69 (2017).
L. Guo, D. Xiao, W. Wu, N. Song, and M. Song: Effect of Fe on microstructure, phase evolution and mechanical properties of (AlCoCrFeNi)100−xFex high entropy alloys processed by spark plasma. Intermetallics 103, 1 (2018).
Y.P. Wang, B.S. Li, M.X. Ren, C. Yang, and H.Z. Fu: Microstructure and compressive properties of AlCrFeCoNi high entropy alloy. Mater. Sci. Eng., A 491, 154 (2008).
A. Sharma, P. Singh, D.D. Johnson, P.K. Liaw, and G. Balasubramanian: Atomistic clustering-ordering and high-strain deformation of an Al0.1CrCoFeNi high-entropy alloy. Sci. Rep. 6, 31028 (2016).
A. Manzoni, H. Daoud, R. Völkl, U. Glatzel, and N. Wanderka: Phase separation in equiatomic AlCoCrFeNi high-entropy alloy. Ultramicroscopy 132, 212 (2013).
L.J. Santodonato, P.K. Liaw, R.R. Unocic, H. Bei, and J.R. Morris: Predictive multiphase evolution in Al-containing high-entropy alloys. Nat. Commun. 9, 4520 (2018).
A. Manzoni, S. Singh, H.M. Daoud, R. Popp, R. Völkl, U. Glatzel, and N. Wanderka: On the path to optimizing the Al—Co—Cr—Cu—Fe—Ni—Ti high entropy alloy family for high temperature applications. Entropy 18, 104 (2016).
C. Zhang, F. Zhang, H. Diao, M.C. Gao, Z. Tang, J.D. Poplawsky, and P.K. Liaw: Understanding phase stability of Al—Co—Cr—Fe—Ni high entropy alloys. Mater. Des. 109, 425 (2016).
K.G. Pradeep, N. Wanderka, P. Choi, J. Banhart, B.S. Murty, and D. Raabe: Atomic-scale compositional characterization of a nanocrystalline AlCrCuFeNiZn high-entropy alloy using atom probe tomography. Acta Mater. 61, 4696 (2013).
O.N. Senkov, J.D. Miller, D.B. Miracle, and C. Woodward: Accelerated exploration of multi-principal element alloys with solid solution phases. Nat. Commun. 6, 6529 (2015).
W. Ji, Z. Fu, W. Wang, H. Wang, J. Zhang, Y. Wang, and F. Zhang: Mechanical alloying synthesis and spark plasma sintering consolidation of CoCrFeNiAl high-entropy alloy. J. Alloy. Comp. 589, 61 (2014).
H. Shiratori, T. Fujieda, K. Yamanaka, Y. Koizumi, K. Kuwabara, T. Kato, and A. Chiba: Relationship between the microstructure and mechanical properties of an equiatomic AlCoCrFeNi high-entropy alloy fabricated by selective electron beam melting. Mater. Sci. Eng., A 656, 39 (2016).
S. Mohanty, T.N. Maity, S. Mukhopadhyay, S. Sarkar, N.P. Gurao, S. Bhowmick, and K. Biswas: Powder metallurgical processing of equiatomic AlCoCrFeNi high entropy alloy: Microstructure and mechanical properties. Mater. Sci. Eng., A 679, 299 (2017).
G. Qin, W. Xue, C. Fan, R. Chen, L. Wang, Y. Su, H. Ding, and J. Guo: Effect of Co content on phase formation and mechanical properties of (AlCoCrFeNi)100−xCox high-entropy alloys. Mater. Sci. Eng., A 710, 200 (2018).
V. Shivam, J. Basu, V. Pandey, Y. Shadangi, and N.K. Mukhopadhyay: Alloying behaviour, thermal stability and phase evolution in quinary AlCoCrFeNi high entropy alloy. Adv. Powder Technol. 29, 2221 (2018).
M. Vaidya, A. Prasad, A. Parakh, and B.S. Murty: Influence of sequence of elemental addition on phase evolution in nanocrystalline AlCoCrFeNi: Novel approach to alloy synthesis using mechanical alloying. Mater. Des. 126, 37 (2017).
N. Eißmann, B. Klöden, T. Weißgärber, and B. Kieback: High-entropy alloy CoCrFeMnNi produced by powder metallurgy. Powder Metall. 60, 184 (2017).
Y. Liu, J. Wang, Q. Fang, B. Liu, Y. Wu, and S. Chen: Preparation of superfine-grained high entropy alloy by spark plasma sintering gas atomized powder. Intermetallics 68, 16 (2016).
R.B. Mane and B.B. Panigrahi: Sintering mechanisms of mechanically alloyed CoCrFeNi high-entropy alloy powders. J. Mater. Res. 33, 3321 (2018).
R.B. Mane and B.B. Panigrahi: Effect of alloying order on non-isothermal sintering kinetics of mechanically alloyed high entropy alloy powders. Mater. Lett. 217, 131 (2018).
K.Y. Tsai, M.H. Tsai, and J.W. Yeh: Sluggish diffusion in Co—Cr—Fe—Mn—Ni high-entropy alloys. Acta Mater. 61, 4887 (2013).
Z. Tang, O.N. Senkov, C.M. Parish, C. Zhang, F. Zhang, L.J. Santodonato, G. Wang, G. Zhao, F. Yang, and P.K. Liaw: Tensile ductility of an AlCoCrFeNi multi-phase high entropy alloy thorough hot isostatic pressing (HIP) and homogenization. Mater. Sci. Eng., A 647, 229 (2015).
A. Zhang, J. Han, J. Meng, B. Su, and P. Li: Rapid preparation of AlCoCrFeNi high entropy alloy by spark plasma sintering from elemental powder mixture. Mater. Lett. 181, 82 (2016).
R.M. German: Sintering Theory and Practice (John Wiley and Sons, Inc., New York, 1996).
Authors thank Dr. S.K. Malladi from MSME, IIT Hyderabad, for their help in TEM work.
About this article
Cite this article
Rohila, S., Mane, R.B., Ummethala, G. et al. Nearly full-density pressureless sintering of AlCoCrFeNi-based high-entropy alloy powders. Journal of Materials Research 34, 777–786 (2019). https://doi.org/10.1557/jmr.2019.9