Processing-dependent stabilization of a dissimilar rare-earth boride in high-entropy (Ti0.2Zr0.2Hf0.2Ta0.2Er0.2)B2 with enhanced hardness and grain boundary segregation

Qin, Mingde; Shivakumar, Sashank; Lei, Tianjiao; Gild, Joshua; C., Hessong, Esther; Wang, Haoren; Vecchio, Kenneth S.; Rupert, Timothy J.; Luo, Jian

doi:10.1016/j.jeurceramsoc.2022.05.034

Cited by 13 publications

(5 citation statements)

References 53 publications

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“…Most multicomponent borides have heterogeneities consisting of B 4 C, graphite, (Zr/Hf)O 2 , and segregates of unitary or mixed-phase borides. – These heterogeneities emerge at grain boundaries and improve the structural properties relative to those of their single-phase counterparts. These impurities get impregnated during material synthesis, typically via mechanical alloying and sintering of metal oxides in the presence of B 4 C. Monitoring and precise control of the proportion of such impurities is challenging; hence, estimating the hardness of a pure single-phase material devoid of grain boundary segregations is difficult and requires optimal synthesis methods that minimize exposure to oxide and carbonaceous contents. ,,– , A widely reported multicomponent boride (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Ti 0.2 )B 2 has been reported to possess hardness between 16.4 and 25.4 GPa from experimental measurements, ,,,,,,– with its single phase chemistry assuming 16.4 and 20.9 GPa per the literature. Similarly, the hardness of another multicomponent boride (Hf 0.2 Zr 0.2 Ti 0.2 Ta 0.2 Cr 0.2 )B 2 is recorded to range from 19.9 to 29.3 GPa, while its single-phase structures have a hardness between 19.9 and 25.4 GPa. ,,, A case in point is that single-phase multicomponent borides have a lower hardness relative to their precursor metal diborides.…”

Section: Resultsmentioning

confidence: 99%

“…These impurities get impregnated during material synthesis, typically via mechanical alloying and sintering of metal oxides in the presence of B 4 C. Monitoring and precise control of the proportion of such impurities is challenging; hence, estimating the hardness of a pure single-phase material devoid of grain boundary segregations is difficult and requires optimal synthesis methods that minimize exposure to oxide and carbonaceous contents. 14 , 24 , 28 – 31 , 43 A widely reported multicomponent boride (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Ti 0.2 )B 2 has been reported to possess hardness between 16.4 and 25.4 GPa from experimental measurements, 14 , 21 , 22 , 24 , 29 , 31 , 44 – 46 with its single phase chemistry assuming 16.4 46 and 20.9 GPa 43 per the literature. Similarly, the hardness of another multicomponent boride (Hf 0.2 Zr 0.2 Ti 0.2 Ta 0.2 Cr 0.2 )B 2 is recorded to range from 19.9 to 29.3 GPa, while its single-phase structures have a hardness between 19.9 and 25.4 GPa.…”

Section: Resultsmentioning

confidence: 99%

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Electronic and Lattice Distortions Induce Elastic Softening in Refractory Multicomponent Borides

Sharma,

Balasubramanian

2023

Chem. Mater.

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Borides are extensively employed in applications demanding exceptionally high hardness, which arises from the unique and strong crystallographic arrangement of boron atoms therein. Addition of multiprincipal elements in borides is expected to enhance their structural properties due to lattice distortion and high configurational entropy. In contrast, we unravel a phenomenon of elastic softening in refractory multicomponent borides from first-principle predictions, which concur with experimentally determined metrics in their single-phase multiprincipal element counterparts. The reductions in the bulk and Young's modulus of these compounds are attributed to the lengthening and distortion of the boron−boron bonds and angles, but more critically to the perturbation in the charge densities arising from the different cations and the consequential increase in statistical weights of the d 5 configuration states of the transition metals present in the boride..

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Electronic and Lattice Distortions Induce Elastic Softening in Refractory Multicomponent Borides

Sharma,

Balasubramanian

2023

Chem. Mater.

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“…The addition of nano-WC particles and La 2 O 3 to La in the Ni-mass percentage 60%WC via a laser process correspondingly enhances the uniformity of the coating, the refinement of the microstructure, and the microhardness of the laser coating [ 18 ]. A content of 20% rare earth Er can be stabilized in high-entropy transition metal borides [ 19 ]. The 10 wt.% Cr + 2 wt.% high chromium and multi-walled carbon nanotubes WC-CoCr coatings show the highest wear resistance [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Stress Distribution in Wear Analysis of Nano-Y2O3 Dispersion Strengthened Ni-Based μm-WC Composite Material Laser Coating

Tao,

Yang,

Zhu

et al. 2023

Materials

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Oxide-dispersion- and hard-particle-strengthened (ODS) laser-cladded single-layer multi-tracks with a Ni-based alloy composition with 20 wt.% μm-WC particles and 1.2 wt.% nano-Y2O3 addition were produced on ultra-high-strength steel in this study. The investigation of the composite coating designed in this study focused on the reciprocating friction and wear workpiece surface under heavy load conditions. The coating specimens were divided into four groups: (i) Ni-based alloy, nano-Y2O3, and 2 μm-WC (2 μm WC-Y/Ni); (ii) Ni-based alloy with added 2 μm-WC (2 μmWC/Ni); (iii) Ni-based alloy with added 80 μm-WC (80 μmWC/Ni); and (iv) base metal ultra-high-strength alloy steel 30CrMnSiNi2A. Four conclusions were reached: (1) Nano-Y2O3 could effectively inhibit the dissolution of 2 μm-WC. (2) It can be seen from the semi-space dimensionless simulation results that the von Mises stress distribution of the metal laser composite coating prepared with a 2 μm-WC particle additive was very uniform and it had better resistance to normal impact and tangential loads than the laser coating prepared with the 80 μm-WC particle additive. (3) The inherent WC initial crack and dense stress concentration in the 80 μm-WC laser coating could easily cause dislocations to accumulate, as shown both quantitatively and qualitatively, resulting in the formation of micro-crack nucleation. After the end of the running-in phase, the COF of the 2 μm-WC-Y2O3/Ni component samples stabilized at the minimum of the COF of the four samples. The numerical order of the four COF curves was stable from small to large as follows: 2 μm-WC-Y2O3/Ni, 2 μm-WC/Ni, 80 μm-WC/Ni, and 30CrMnSiNi2A. (4) The frictional volume loss rate of 2 μm-WC-Y2O3/Ni was 1.3, which was significantly lower than the corresponding values of the other three components: 2.4, 3.5, and 13.

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“…High‐entropy ceramics have attracted a lot of attention from researchers in recent years 1–4 . As a derivative of diboride ceramics, the high‐entropy diboride ceramics (HEBs) have inherited the advantages of the single‐component transition metal diboride ceramics (high melting point, oxidation resistance, and ablation resistance) 5–13 . Their low thermal conductivity caused by inherent lattice distortion is also attractive for the application in the field of ultrahigh temperature thermal protection 14–16 .…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4] As a derivative of diboride ceramics, the high-entropy diboride ceramics (HEBs) have inherited the advantages of the single-component transition metal diboride ceramics (high melting point, oxidation resistance, and ablation resistance). [5][6][7][8][9][10][11][12][13] Their low thermal conductivity caused by inherent lattice distortion is also attractive for the application in the field of ultrahigh temperature thermal protection. [14][15][16] Gild et al 14 prepared three dense singlephase 5-cation HEBs of (Hf 1/5 Zr 1/5 Ti 1/5 Ta 1/5 M 1/5 )B 2 , where M = Nb, Mo, Cr and measured their thermal conductivity to be 24.8, 15.2, and 12.6 W m −1 K −1 at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity of equiatomic high‐entropy diboride ceramics with 5–9 cations

Liu

Qin

et al. 2023

Int J Applied Ceramic Tech

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As a new type of high-entropy material, most of the current work has focused on the synthesis and characterization of mechanical properties of high-entropy diboride ceramics (HEBs). In this work, single-phase HEBs with 5-9 cations were prepared by spark plasma sintering with self-synthesized HEB powders through the boro/carbothermal reduction method. The distribution of the metal elements in the obtained HEBs was homogeneous. Due to the phonon scattering caused by the inherent lattice distortion in the HEBs, the thermal conductivity of the ceramics decreased with the increased configurational entropy or the number of cation kinds. However, this study reveals that the degree of reduction in thermal conductivity for the HEBs demonstrate a weakened tendency with cation kinds of more than 6.

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Processing-dependent stabilization of a dissimilar rare-earth boride in high-entropy (Ti0.2Zr0.2Hf0.2Ta0.2Er0.2)B2 with enhanced hardness and grain boundary segregation

Cited by 13 publications

References 53 publications

Electronic and Lattice Distortions Induce Elastic Softening in Refractory Multicomponent Borides

Electronic and Lattice Distortions Induce Elastic Softening in Refractory Multicomponent Borides

Stress Distribution in Wear Analysis of Nano-Y2O3 Dispersion Strengthened Ni-Based μm-WC Composite Material Laser Coating

Thermal conductivity of equiatomic high‐entropy diboride ceramics with 5–9 cations

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