Hard, Superhard and Ultrahard Materials: An Overview

Kanyanta, Valentine

doi:10.1007/978-3-319-29291-5_1

Cited by 9 publications

(10 citation statements)

References 63 publications

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“…Few materials in existence exhibit a superhard behavior, defined as having a Vickers hardness ( H V ) exceeding 40 GPa. − Diamond is, of course, the hardest naturally occurring mineral with a Mohs hardness of 10 and a H V ≈ 90 GPa. , Other synthetic superhard materials such as cubic boron nitride ( H V = 60 GPa), BC 2 N ( H V = 71 GPa), and BC 5 ( H V = 79 GPa) have also been discovered, while a myriad of additional phases such as B 4 C 4 ( H V = 52 GPa), BC 3 ( H V = 62 GPa), and B 2 CO ( H V = 50) have been computationally predicted to be superhard using genetic algorithms. The common connection among these materials is strong, covalent bonding between light elements.…”

Section: Introductionmentioning

confidence: 99%

Treating Superhard Materials as Anomalies

Zhang

Brgoch

2022

J. Am. Chem. Soc.

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Superhard materials are among the most scarce functional inorganic solids in existence. Indeed, recent research suggested that less than 0.1% of all known materials are likely to have a Vickers hardness ≥40 GPa. Here, an anomaly detection framework is created to treat these materials as rare occurrences by encoding and reconstructing the input composition and crystal structure information without supervision. The resulting model can quantitatively identify outliers from "normal" behaving materials, leading to the discovery of materials with exceptional properties such as a superhard response. Moreover, examining the difference between the encoded and decoded crystal structure provides fundamental insights into the crystal-chemical origin of hardness. The presented methodology is ultimately generalizable, enabling the design of other outlier materials with rare and unexpected physical properties.

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Section: Introductionmentioning

confidence: 99%

Treating Superhard Materials as Anomalies

Zhang

Brgoch

2022

J. Am. Chem. Soc.

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“…One of the common features of these transition metal borides is their high values of hardness. [1][2][3][4] Hard, superhard, and ultrahard materials largely belong to the oxides, borides, nitrides, carbides of metals. In addition nonmetallic cermets, carbon nitrides, cubic boron nitrides (c-BN) are also widely used.…”

Section: Introductionmentioning

confidence: 99%

“…In addition nonmetallic cermets, carbon nitrides, cubic boron nitrides (c-BN) are also widely used. [1] For large-scale industrial applications as hard materials, high value of hardness, high incompressibility, and chemical inertness are the main requirements.…”

Section: Introductionmentioning

confidence: 99%

“…[6] Almost all of the metallic borides show high levels of hardness and particularly the binary diborides like RuB 2 and OsB 2 are considered to be superhard and ultra-incompressible. [1][2][3][4] The ReB 2 is expected to be able to scratch even diamond. [7,8] Transition metal borides often show refractory behavior and chemical inertness suitable for heavy duty coarse condition applications.…”

Section: Introductionmentioning

confidence: 99%

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Elastic, thermodynamic, electronic, and optical properties of recently discovered superconducting transition metal boride NbRuB: An ab-initio investigation

Parvin¹,

Naqib²

2017

Chinese Phys. B

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The elastic, thermodynamic, electronic, and optical properties of recently discovered and potentially technologically important transition metal boride NbRuB, have been investigated using the density functional formalism. Both generalized gradient approximation (GGA) and local density approximation (LDA) were used for geometrical optimization and for estimation of various elastic moduli and constants.The optical properties of NbRuB have been studied for the first time with different photon polarizations.The frequency (energy) dependences of various optical constants compliment quite well to the essential features of the electronic band structure calculations. Debye temperature of NbRuB has been estimated form the thermodynamical study. All these theoretical estimates have been compared with published results, where available, and discussed in detail. Both electronic band structure and optical conductivity reveal robust metallic characteristics. NbRuB possesses significant elastic and electronic anisotropy. The effects of electronic band structure and Debye temperature on the emergence of superconductivity have also been analyzed.

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“…Structural materials that operate at elevated temperatures are vital for a myriad of industrial applications, such as engine exhaust valves and high-speed bearings. , These materials, specifically high hardness materials, are also essential for numerous construction and manufacturing purposes like cutting, drilling, and as abrasives for grinding. , Conventional high hardness materials, including classically known diamond-type materials (diamond, c -BN) , and more recently transition metal borides (ReB 2 and WB 4 ), , each possess an impressive room temperature Vickers hardness ( H V ) that is ≥40 GPa depending on the applied load. However, during the operation of these materials, tremendous forces are experienced, generating extreme heat.…”

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confidence: 99%

Determining Temperature-Dependent Vickers Hardness with Machine Learning

Zhang

Brgoch

2021

J. Phys. Chem. Lett.

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Assessing the hardness of structural materials at elevated temperatures is experimentally and computationally challenging, yet crucial for their success. In this work, a machine-learning method was developed to determine a material's temperature-dependent hardness based on its chemical composition and crystal structure. A total of 593 Vickers hardness data collected at various temperatures were extracted from the literature and used to train an extreme gradient boosting (XGBoost) machine-learning model. Applying a combination of composition descriptors and smooth overlap of atomic positions (SOAP) structural descriptors to represent these materials resulted in outstanding accuracy (R 2 = 0.91; MAE = 2.52 GPa). The model's intrinsic variance was also measured by using a bootstrap aggregating (bagging) method, and the subsequent predictions showed strong agreement with the experimental data. The capability of the trained model was finally verified by demonstrating the model's ability to discriminate polymorphs, separate the properties of similar compositions, and reproduce the high-temperature hardness of several classic structural materials.

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Hard, Superhard and Ultrahard Materials: An Overview

Cited by 9 publications

References 63 publications

Treating Superhard Materials as Anomalies

Treating Superhard Materials as Anomalies

Elastic, thermodynamic, electronic, and optical properties of recently discovered superconducting transition metal boride NbRuB: An ab-initio investigation

Determining Temperature-Dependent Vickers Hardness with Machine Learning

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