PSI - Issue 30

M.N. Safonova et al. / Procedia Structural Integrity 30 (2020) 136–143

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Safonova M.N. et al. / Structural Integrity Procedia 00 (2020) 000–000

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1. Introduction It is known that a high level of physic-mechanical properties of diamond powders is determined by a larger specific surface area and grain dispersion, which, in particular, directly follows from the Hall-Petch equation, which is fulfilled in a wide (up to 1 μ m) size range grains. The decisive factor for the functional properties of these materials is a large-scale structural factor, since it affects the formation of structurally sensitive mechanical properties - ultimate strength and yield strength as shown by Yemelyanova et al. (2017), Ivanov et al. (2009). Given the qualitative correlation between yield strength and hardness, it is possible to predict an increase in hardness, including superhard materials - the finer the filler, the less defects in it, the higher the strength.

Nomenclature NDP

natural diamond powder UDND ultra disperse natural diamond Δ G o change of the Gibbs energy σ пр

proportionality limit in compression

ρ факт

actual density

E с П

compression modulus

porosity

Т  the theoretical (calculated) density of nonporous material; ρ is the actual density of the sample 1 C concentration of copper in the powder mixtures according to its density 2 C concentration of tin in the powder mixtures according to its density 3 C concentration of NDP in the powder mixtures according to its density 4 C concentration of UDND in the powder mixtures according to its density 1  density of copper 2  density of tin 3  density of NDP 4  density of UDND 1 m mass in air 2 m mass in water ж  liquid density V pressing volume  nearest distance between the particles G shear modulus b Burgers vector 0 k coefficient characterizing the pattern of interacting atoms with dislocation H L the weight fraction of filler d the diameter or thickness of filler particles k Hall – Petch coefficient з d grain size общ S total area of objects общ N total number of objects Т   gain of yield strength The hardening mechanisms in such materials depend on the nature of the interaction of the introduced particles or fibers of the hardener with the matrix material. The successful application of the effect of dispersed hardening is given in the original works by Kallip et al. (2017), Jiang et al. (2017), Liu et al. (2017), Saba et al. (2019), Mokdad et al. (2017). The hardening of dispersion-hardened materials consists in creating a structure in them that impedes the movement of dislocations. The strongest drag on the movement of dislocations is created by discrete particles of the second phase, characterized by high strength and melting point. Given the two-phase structure and high hardness of the resulting materials, it is expected that their wear resistance will also be higher than that of conventional non-