A novel non-stoichiometric medium-entropy carbide stabilized by anion vacancies

doi:10.1016/j.jmst.2020.02.049

Abstract

Abstract:

Recently, high-entropy ceramics have attracted considerable attentions because of comprehensive physical and chemical properties of high hardness, fracture toughness, and conductivity. However, as a newly emerging class of materials, the synthesis, performance and applications of high-entropy ceramics are subject to further development. Here, we reported a new non-stoichiometric TiC_0.4/WC/0.5Mo₂C medium-entropy carbide (MEC) with a rock-salt structure. Attributed to the solid solution strengthening and twinning strengthening, the TiC_0.4/WC/0.5Mo₂C sintered at 1900 °C by spark plasma sintering (SPS) shows superior mechanical behaviors of microhardness (21.7 GPa), which exceeds that expected from the rule of mixture (ROM) of three individual metal carbides (19.1 GPa) and good fracture toughness (5.3 MPa m ^1/2). Significantly, the bulk synthesized via high-pressure and high-temperature (HPHT) sintering possesses smaller grain size and shows better comprehensive mechanical properties of microhardness (23.7 GPa) and fracture toughness (6.2 MPa m ^1/2). In addition, the effect of anion vacancies on the thermodynamic stability and synthesizability of TiC_0.4/WC/0.5Mo₂C was analyzed via quantitatively calculated entropy. Vacancies could significantly enhance the configurational entropy of mixing of the solid phase. The introduction of vacancy defects may expand synthetic path for entropy-stabilized ceramics, especially for multi-component high temperature refractory ceramics.

Key words: Anion vacancies, Medium-entropy carbide, Solid solution strengthening, Twinning

Chong Peng, Hu Tang, Yu He, Xiaoqian Lu, Peng Jia, Guoying Liu, Yucheng Zhao, Mingzhi Wang. A novel non-stoichiometric medium-entropy carbide stabilized by anion vacancies[J]. J. Mater. Sci. Technol., 2020, 51: 161-166.

Figures/Tables 4

Fig. 1. Compositional analysis and microstructural characterization. XRD patterns of TiC/WC/0.5Mo2C and TiC0.4/WC/0.5Mo2C at different temperatures (a) and details of (111) and (200) peaks (b); (c) The back-scattered electron (BSE) image of TiC0.4/WC/0.5Mo2C synthesized at 1900 °C; (d-f) Energy disperse spectroscopy (EDS) maps acquired from the marked area of (c): (d) Ti; (e) W; (f) Mo.

Fig. 2. TEM analysis of TWMC19. (a) HAADF-STEM image and SAED pattern in the inset; (b) Typical HRTEM image; (c, d) The IFFT and FFT images domain in the marked area of (b); (e-g) EDS compositional maps acquired from the marked area of (a): (e) Ti; (f) W; (g) Mo.

Fig. 3. Comparison of mechanical properties. (a) The measured Vickers hardness of TWMC19 as a function of applied load. Inset: an optical micrograph of the Vickers indentation with cracks produced at a load of 9.8 N. (b) Comparison of the mechanical properties of TiC0.4/WC/0.5Mo2C with binary precursor carbides. Error bars shown in the plot represent standard deviation of the data.

Fig. 4. Schematics of calculated configurational entropy. (a) Dependence of configurational entropy on the non-stoichiometric precursor component and the content of Mo2C; (b) The comparison of configurational entropy in an N-component compounds.

References 31

[1]	M.H. Tsai, J.W. Yeh , Mater. Res. Lett., 2(2014), pp. 107-123.
[2]	L. Jiang, H. Jiang, Y. Lu, T. Wang, Z. Cao, T. Li, J. Mater. Sci. Technol., 31(2015), pp. 397-402.
[3]	J.W. Yeh, S.K. Chen, S.J. Lin, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau, S.Y. Chang , Adv. Eng. Mater., 6(2004), pp. 299-303.
[4]	L. Jiang, Y. Lu, W. Wu, Z. Cao, T. Li, J. Mater. Sci. Technol., 32(2016), pp. 245-250.
[5]	D.B. Miracle, O.N. Senkov , Acta Mater., 122(2017), pp. 448-511.
[6]	A. Sarkar, Q. Wang, A. Schiele, M.R. Chellali, S.S. Bhattacharya, D. Wang, T. Brezesinski, H. Hahn, L. Velasco, B. Breitung, Adv. Mater., 31 ( 2019), Article 1806236.
[7]	C.M. Rost, E. Sachet, T. Borman, A. Moballegh, E.C. Dickey, D. Hou, J.L. Jones, S. Curtarolo, J.P. Maria , Nat. Commun., 6(2015), p. 8485.
[8]	E. Castle, T. Csanádi, S. Grasso, J. Dusza, M. Reece , Sci. Rep., 8(2018), p. 8609.
[9]	J. Dusza, P. vec, V. Girman, R. Sedlák, E.G. Castle, T. Csanádi, A. Kovalíková, M.J. Reece, J. Eur. Ceram. Soc., 38(2018), pp. 4303-4307.
[10]	B. Ye, T. Wen, M.C. Nguyen, L. Hao, C. Wang, Y. Chu , Acta Mater., 170(2019), pp. 15-23.
[11]	P. Sarker, T. Harrington, C. Toher, C. Oses, M. Samiee, J.P. Maria, D.W. Brenner, K.S. Vecchio, S. Curtarolo , Nat. Commun., 9(2018), p. 4980.
[12]	J. Gild, Y. Zhang, T. Harrington, S. Jiang, T. Hu, M.C. Quinn, W.M. Mellor, N. Zhou, K. Vecchio, J. Luo , Sci. Rep., 6(2016), p. 37946.
[13]	T. Wen, S. Ning, D. Liu, B. Ye, H. Liu, Y. Chu, J. Am. Ceram. Soc., 102(2019), pp. 4956-4962.
[14]	T. Jin, X. Sang, R.R. Unocic, R.T. Kinch, X. Liu, J. Hu, H. Liu, S. Dai, Adv. Mater., 30 ( 2018), Article 1707512.
[15]	R. Zhang, F. Gucci, H. Zhu, K. Chen, M.J. Reece , Inorg. Chem., 57(2018), pp. 13027-13033.
[16]	H. Chen, H. Xiang, F. Dai, J. Liu, Y. Lei, J. Zhang, Y. Zhou, J. Mater. Sci. Technol., 35(2019), pp. 1700-1705.
[17]	C. Peng, X. Gao, M. Wang, L. Wu, H. Tang, X. Li, Q. Zhang, Y. Ren, F. Zhang, Y. Wang, B. Zhang, B. Gao, Q. Zou, Y. Zhao, Q. Yang, D. Tian, H. Xiao, H. Gou, W. Yang, X. Bai, W.L. Mao, H. Mao, Appl. Phys. Lett., 114 ( 2019),Article 011905.
[18]	Q. Hong, A. van de Walle, Phys. Rev. B, 92 ( 2015)020104(R).
[19]	L. Qiao, M. Wang, M. Liu, Y. Zhao, Q. Yang, Q. Zou, X. Wang, L. Wang, H. Guo , Ceram. Int., 41(2015), pp. 11341-11345.
[20]	Z. Zhang, C. Geng, Y. Ke, C. Li, X. Jiao, Y. Zhao, H. Tang, M. Wang , Ceram. Int., 44(2018), pp. 18996-19001.
[21]	J. Freudenberger, D. Rafaja, D. Geissler, L. Giebeler, C. Ullrich, A. Kauffmann, M. Heilmaier, K. Nielsch , Metals, 7(2017), p. 135.
[22]	G.K. Williamson, W.H. Hall , Acta Metall., 1(1953), pp. 22-31.
[23]	G.R. Anstis, P. Chantikul, B.R. Lawn, D.B. Marshall, J. Am. Ceram. Soc., 64(1981), pp. 533-538.
[24]	G.M. Pharr, W.C. Oliver , MRS Bull., 17(1992), pp. 28-33.
[25]	T.J. Harrington, J. Gild, P. Sarker, C. Toher, C.M. Rost, O.F. Dippo, C. McElfresh, K. Kaufmann, E. Marin, L. Borowski, P.E. Hopkins, J. Luo, S. Curtarolo, D.W. Brenner, K.S. Vecchio , Acta Mater., 166(2019), pp. 271-280.
[26]	Z. Wang, I. Baker, Z. Cai, S. Chen, J.D. Poplawsky, W. Guo , Acta Mater., 120(2016), pp. 228-239.
[27]	K. Lu, L. Lu, S. Suresh , Science, 324(2009), pp. 349-352.
[28]	H. Tang, X. Yuan, P. Yu, Q. Hu, M. Wang, Y. Yao, L. Wu, Q. Zou, Y. Ke, Y. Zhao, L. Wang, X. Li, W. Yang, H. Gou, H. Mao, W.L. Mao , Carbon, 129(2018), pp. 159-167.
[29]	Q. Huang, D. Yu, B. Xu, W. Hu, Y. Ma, Y. Wang, Z. Zhao, B. Wen, J. He, Z. Liu, Y. Tian , Nature, 510(2014), pp. 250-253.
[30]	V.I. Razumovskiy, A.V. Ruban, J. Odqvist, D. Dilner, P.A. Korzhavyi , Calphad, 46(2014), pp. 87-91.
[31]	S. Xu, M. Wang, L. Qiao, Y. Ye, G. Jia, Y. Zhao , Adv. Appl. Ceram., 114(2014), pp. 256-260.