Crystal Indentation Hardness

Abstract

Abstract:There is expanded interest in the long-standing subject of the hardness properties of materials. A major part of such interest is due to the advent of nanoindentation hardness testing systems which have made available orders of magnitude increases in load and displacement measuring capabilities achieved in a continuously recorded test procedure. The new results have been smoothly merged with other advances in conventional hardness testing and with parallel developments in improved model descriptions of both elastic contact mechanics and dislocation mechanisms operative in the understanding of crystal plasticity and fracturing behaviors. No crystal is either too soft or too hard to prevent the determination of its elastic, plastic and cracking properties under a suitable probing indenter. A sampling of the wealth of measurements and reported analyses associated with the topic on a wide variety of materials are presented in the current Special Issue.

Is it possible to predict the stability of a crystal structure under the influence of pressure? Quantum chemical study of ibuprofen crystals

“…Compression leads to the compaction of the API's crystal structure due to conformational and orientational changes. 27 The influence of pressure on a crystal structure can be studied by experimental methods such as the nanoindentation method (anisotropic compression) 28 or the method of isotropic compression in a diamond anvil cell (DAC). 29,30 Quantum chemical calculations are commonly used to explain or predict the results of experimental methods.…”

Quantum Chemical Modeling of Mechanical Properties of Aspirin Polymorphic Modifications

“…Mechanical properties of molecular crystals are studied by both experimental and theoretical methods. The nanoindentation method and the diamond anvil cell technique , are the most used experimental methods. Each of them has its own merits and shortcomings, but both experimental methods require special expensive equipment.…”

Study of Hardness of Superhard Crystals by Topological Indices

“…where n i is the position in the form of a number of the ith atom in the unit cell, Z i is the valence electron number of the ith atom crediting to the covalent bond, and V is the volume of the unit cell. More results on the hardness (various definitions of hardness) study of crystals can be referred to Suzuki et al [4], Armstrong et al [5], Mamun et al [6], Shkir et al [7], and Palatnikov et al [8]. Now, if we talk about the unit crystals studied in this article, then the first one is BC 2 , and by the first-principles computations, BC 2 was predicted originally from (a kind of tetragonal phase) the cubic diamond structure.…”