Towards the theory of hardness of materials

  title={Towards the theory of hardness of materials},
  author={Artem R. Oganov and Andriy O. Lyakhov},
  journal={Journal of Superhard Materials},
Recent studies have shown that hardness, a complex property, can be calculated using very simple approaches or even analytical formulae. These form the basis for evaluating controversial experimental results (as we illustrate for TiO2-cotunnite) and enable a systematic search for novel hard materials, for instance, using global optimization algorithms (as we show on the example of SiO2 polymorphs). 

Search for superhard carbon: between graphite and diamond

A brief review has been presented of the recent studies aimed at searching for new 3D (sp3) carbon allotropes of increased hardness and carried out using computational approaches. The principles of

3.04 – Theory of Superhard Materials

First-principles structural design of superhard materials.

This work adopted hardness as the fitness function in combination with the first-principles calculation to construct the hardness vs. energy map by seeking a proper balance between hardness and energy for a better mechanical description of given chemical systems.

Experimental study and critical review of structural, thermodynamic and mechanical properties of superhard refractory boron suboxide B6O

In the present study the analysis of available data on structural, thermodynamic and mechanical properties of B6O has been performed. Although the compound is known for half a century and has been

Hardness of T-carbon: Density functional theory calculations

We reconsider and interpret the mechanical properties of the recently proposed allotrope of carbon, T-carbon [Sheng et al., Phys. Rev. Lett. 106, 155703 (2011)], using density functional theory in

Reflection of strengthening results in values of generalized degrees of metallicity and covalence is principle to new strategy of designing alloys

A method for predicting new doping systems for dispersively strengthening aluminum alloys according to the criterion of a given strength is considered and the methodology of optimizing chemical composition in steel smelting which is used for mass production of parts is considered according toThe criterion of the desired mechanical properties obtained due to solid solution hardening.

First-principle calculations on the structural stability and electronic properties of superhard BxCy compounds

  • M. LiXiaofeng FanW. Zheng
  • Materials Science, Chemistry
    Journal of physics. Condensed matter : an Institute of Physics journal
  • 2013
It is found that the hardness of the B-C system has a decreasing trend with the increase of boron concentration, and the bonds with high electron density and short bond length have an important contribution to the hardness in the BxCy system.

Computational materials discovery: the case of the W-B system.

The results show that, among these borides, hP6-WB2 exhibits the largest ultra-incompressibility along the c axis, with the highest C33 value (953 GPa, comparable with that of the most incompressible diamond).

The Role Played by Computation in Understanding Hard Materials

In the present work the importance of both ab-initio approaches and molecular dynamics aspects will be discussed with application to quite different systems.



Intrinsic hardness of crystalline solids

The current status of various theoretical approaches to the “prediction” of material hardness has been reviewed. It is shown that the simple empirical correlation with the shear moduli generally

Microscopic models of hardness

Recent developments in the field of microscopic hardness models have been reviewed. In these models, the theoretical hardness is described as a function of the bond density and bond strength. The

Hardness of covalent crystals.

A semiempirical method for the evaluation of hardness of multicomponent crystals is presented and it is found that bond density or electronic density, bond length, and degree of covalent bonding are three determinative factors for the hardness of a polar covalents crystal.

On the hardness of a new boron phase, orthorhombic γ-B28

Measurements of the hardness of a new high-pressure boron phase, orthorhombic γ-B28, are reported. According to the data obtained, γ-B28 has the highest hardness (∼ 50 GPa) of all known crystal-line

Hardness of covalent and ionic crystals: first-principle calculations.

It is shown that a lower coordination number of atoms results in higher hardness, contrary to common opinion presented in general literature.

Materials science: The hardest known oxide

The discovery of a cotunnite-structured titanium oxide which represents the hardest oxide known is reported, which is one of the least compressible and hardest polycrystalline materials to be described.

Thermodynamic model of hardness: Particular case of boron-rich solids

A number of successful theoretical models of hardness have been developed recently. A thermodynamic model of hardness, which supposes the intrinsic character of correlation between hardness and

Predicting new superhard phases

The search for new superhard materials is of great importance in view of their major roles played for the fundamental science and the industrial applications. Recent experimental synthesis has made

Origin of Superhardness in Icosahedral B12 Materials.

Boron-rich phases with icosahedral symmetry are quite intriguing. It is important to understand the origin of hardness of boron-rich materials. By starting from a chemical bond viewpoint, a simple