Softening of ultra-nanocrystalline diamond at low grain sizes

Autor:	Remediakis, Ioannis N., Kopidakis, Georgios, Kelires, Pantelis C.
Rok vydání:	2008
Předmět:	Condensed Matter - Materials Science
Druh dokumentu:	Working Paper
Popis:	Ultra-nanocrystalline diamond is a polycrystalline material, having crystalline diamond grains of sizes in the nanometer regime. We study the structure and mechanical properties of this material as a function of the average grain size, employing atomistic simulations. From the calculated elastic constants and the estimated hardness, we observe softening of the material as the size of its grains decreases. We attribute the observed softening to the enhanced fraction of interfacial atoms as the average grain size becomes smaller. We provide a fitting formula for the scaling of the cohesive energy and bulk modulus with respect to the average grain size. We find that they both scale as quadratic polynomials of the inverse grain size. Our formulae yield correct values for bulk diamond in the limit of large grain sizes. Comment: 5 pages, 3 figures, to be published in Acta Materialia
Databáze:	arXiv
Externí odkaz:	http://arxiv.org/abs/0807.2410 Zobrazit plný text záznamu View this record from Arxiv