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High-entropy ceramics attract more and more attention in recent years. However, mechanical properties especially strength and fracture toughness for high-entropy ceramics and their composites have not been comprehensively reported. In this work, high-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2 (HEB) monolithic and its composite containing 20 vol% SiC (HEB-20SiC) are prepared by hot pressing. The addition of SiC not only accelerates the densification process but also refines the microstructure of HEB, resulting in improved mechanical properties. The obtained dense HEB and HEB-20SiC ceramics hot pressed at 1800 ℃ exhibit four-point flexural strength of 339±17 MPa and 447±45 MPa, and fracture toughness of 3.81±0.40 MPa·m1/2 and 4.85±0.33 MPa·m1/2 measured by single-edge notched beam (SENB) technique. Crack deflection and branching by SiC particles is considered to be the main toughening mechanisms for the HEB-20SiC composite. The hardness Hv0.2 of the sintered HEB and HEB-20SiC ceramics is 23.7±0.7 GPa and 24.8±1.2 GPa, respectively. With the increase of indentation load, the hardness of the sintered ceramics decreases rapidly until the load reaches about 49 N, due to the indentation size effect. Based on the current experimental investigation it can be seen that the room temperature bending strength and fracture toughness of the high-entropy diboride ceramics are within ranges commonly observed in structure ceramics.


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Mechanical properties of hot-pressed high-entropy diboride-based ceramics

Show Author's information Ji-Xuan LIUXiao-Qin SHENYue WUFei LIYongcheng LIANGGuo-Jun ZHANG( )
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, College of Sciences, Institute of Functional Materials, Donghua University, Shanghai 201620, China

Abstract

High-entropy ceramics attract more and more attention in recent years. However, mechanical properties especially strength and fracture toughness for high-entropy ceramics and their composites have not been comprehensively reported. In this work, high-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2 (HEB) monolithic and its composite containing 20 vol% SiC (HEB-20SiC) are prepared by hot pressing. The addition of SiC not only accelerates the densification process but also refines the microstructure of HEB, resulting in improved mechanical properties. The obtained dense HEB and HEB-20SiC ceramics hot pressed at 1800 ℃ exhibit four-point flexural strength of 339±17 MPa and 447±45 MPa, and fracture toughness of 3.81±0.40 MPa·m1/2 and 4.85±0.33 MPa·m1/2 measured by single-edge notched beam (SENB) technique. Crack deflection and branching by SiC particles is considered to be the main toughening mechanisms for the HEB-20SiC composite. The hardness Hv0.2 of the sintered HEB and HEB-20SiC ceramics is 23.7±0.7 GPa and 24.8±1.2 GPa, respectively. With the increase of indentation load, the hardness of the sintered ceramics decreases rapidly until the load reaches about 49 N, due to the indentation size effect. Based on the current experimental investigation it can be seen that the room temperature bending strength and fracture toughness of the high-entropy diboride ceramics are within ranges commonly observed in structure ceramics.

Keywords:

high-entropy ceramics, high-entropy diboride, flexural strength, fracture toughness, indentation size effect
Received: 22 February 2020 Revised: 30 April 2020 Accepted: 01 May 2020 Published: 20 May 2020 Issue date: August 2020
References(30)
[1]
JW Yeh, SK Chen, SJ Lin, et al. Nanostructured high-entropy alloys with multiple principal elements: Novel alloy design concepts and outcomes. Adv Eng Mater 2004, 6: 299-303.
[2]
EP George, D Raabe, RO Ritchie. High-entropy alloys. Nat Rev Mater 2019, 4: 515-534.
[3]
J Gild, YY Zhang, T Harrington, et al. High-entropy metal diborides: A new class of high-entropy materials and a new type of ultrahigh temperature ceramics. Sci Rep 2016, 6: 37946-37956.
[4]
Y Zhang, ZB Jiang, SK Sun, et al. Microstructure and mechanical properties of high-entropy borides derived from boro/carbothermal reduction. J Eur Ceram Soc 2019, 39: 3920-3924.
[5]
XQ Shen, JX Liu, F Li, et al. Preparation and characterization of diboride-based high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2-SiC particulate composites. Ceram Int 2019, 45: 24508-24514.
[6]
JF Gu, J Zou, SK Sun, et al. Dense and pure high-entropy metal diboride ceramics sintered from self-synthesized powders via boro/carbothermal reduction approach. Sci China Mater 2019, 62: 1898-1909.
[7]
S Failla, P Galizia, S Fu, et al. Formation of high entropy metal diborides using arc-melting and combinatorial approach to study quinary and quaternary solid solutions. J Eur Ceram Soc 2020, 40: 588-593.
[8]
H Chen, HM Xiang, FZ Dai, et al. Porous high entropy (Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)B2: A novel strategy towards making ultrahigh temperature ceramics thermal insulating. J Mater Sci Tech 2019, 35: 2404-2408.
[9]
P Sarker, T Harrington, C Toher, et al. High-entropy high-hardness metal carbides discovered by entropy descriptors. Nat Commun 2018, 9: 4980.
[10]
E Castle, T Csanádi, S Grasso, et al. Processing and properties of high-entropy ultra-high temperature carbides. Sci Rep 2018, 8: 8609.
[11]
XF Wei, JX Liu, F Li, et al. High entropy carbide ceramics from different starting materials. J Eur Ceram Soc 2019, 39: 2989-2994.
[12]
K Lu, JX Liu, XF Wei, et al. Microstructures and mechanical properties of high-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C ceramics with the addition of SiC secondary phase. J Eur Ceram Soc 2020, 40: 1839-1847.
[13]
CM Rost, E Sachet, T Borman, et al. Entropy-stabilized oxides. Nat Commun 2015, 6: 8485.
[14]
SC Jiang, T Hu, J Gild, et al. A new class of high-entropy perovskite oxides. Scripta Mater 2018, 142: 116-120.
[15]
F Li, L Zhou, JX Liu, et al. High-entropy pyrochlores with low thermal conductivity for thermal barrier coating materials. J Adv Ceram 2019, 8: 576-582.
[16]
Y Dong, K Ren, YH Lu, et al. High-entropy environmental barrier coating for the ceramic matrix composites. J Eur Ceram Soc 2019, 39: 2574-2579.
[17]
Y Qin, JX Liu, F Li, et al. A high entropy silicide by reactive spark plasma sintering. J Adv Ceram 2019, 8: 148-152.
[18]
J Gild, J Braun, K Kaufmann, et al. A high-entropy silicide: (Mo0.2Nb0.2Ta0.2Ti0.2W0.2)Si2. J Materiomics 2019, 5: 337-343.
[19]
XQ Chen, YQ Wu. High-entropy transparent fluoride laser ceramics. J Am Ceram Soc 2020, 103: 750-756.
[20]
F Li, WC Bao, SK Sun, et al. Synthesis of single-phase metal oxycarbonitride ceramics. Scripta Mater 2020, 176: 17-22.
[21]
HB Ma, ZY Man, JX Liu, et al. Microstructures, solid solution formation and high-temperature mechanical properties of ZrB2 ceramics doped with 5vol.% WC. Mater Design 2015, 81: 133-140.
[22]
J Zou, GJ Zhang, H Zhang, et al. Improving high temperature properties of hot pressed ZrB2-20vol% SiC ceramic using high purity powders. Ceram Int 2013, 39: 871-876.
[23]
GJ Zhang, ZZ Jin, XM Yue. TiN-TiB2 composites prepared by reactive hot pressing and effects of Ni addition. J Am Ceram Soc 1995, 78: 2831-2833.
[24]
CS Smith. Introduction to grains, phases, and interfaces— An interpretation of microstructure. Trans AIME 1948, 175: 15-51.
[25]
M Taya, S Hayashi, AS Kobayashi, et al. Toughening of a particulate-reinforced ceramic-matrix composite by thermal residual stress. J Am Ceram Soc 1990, 73: 1382-1391.
[26]
FG Keihn, EJ Keplin. High-temperature thermal expansion of certain group IV and group V diborides. J Am Ceram Soc 1967, 50: 81-84.
[27]
H Li, RC Bradt. The microhardness indentation load/size effect in rutile and cassiterite single crystals. J Mater Sci 1993, 28: 917-926.
[28]
JH Gong, JJ Wu, ZD Guan. Examination of the indentation size effect in low-load Vickers hardness testing of ceramics. J Eur Ceram Soc 1999, 19: 2625-2631.
[29]
DY Jiang. Recent progresses in the phenomenological description for the indentation size effect in microhardness testing of brittle ceramics. J Adv Ceram 2012, 1: 38-49.
[30]
YB Duan, DY Jiang, J Hu. Determination of the load-independent hardness by analyzing the nanoindentation loading curves: A case study on fused silica. J Adv Ceram 2019, 8: 583-586.
Publication history
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Publication history

Received: 22 February 2020
Revised: 30 April 2020
Accepted: 01 May 2020
Published: 20 May 2020
Issue date: August 2020

Copyright

© The Author(s) 2020

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 51532009, 51872045); Science and Technology Commission of Shanghai Municipality (No. 18ZR1401400); the Fundamental Research Funds for the Central Universities (Nos. 2232018D3-32, 2232019A3-13); and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University (No. 19ZK0113).

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