Effect of discrete breathers on plasticity and strength of crystals

Abstract

Рассмотрены модели взаимодействия дислокаций с дискретными бризерами. Атомные колебания большой амплитуды вызывают модуляцию энергии активации отрыва дислокаций от стопоров, что может значительно ускорять пластическую деформацию в условиях доста-точно высокой концентрации бризеров. Такие условия могут реализоваться при облучении кристаллов бы-стрыми частицами или при достаточно высоких темпе-ратурах. Проведено сравнение моделей с эксперимен-тальными данными для ряда металлов. Обсуждается возможная роль дискретных бризеров в процессе термо-активированного разрушения растянутого графена.Ключевые слова: дискретные бризеры, дислокации, пласти-ческая деформация, графен, разрушение.Models of the dislocation interaction with discrete breathers (DB) are considered. Large amplitude oscillations of atoms about their equilibrium positions in the lattice cause time-periodic modulations of the potential barriers for the dislocation unpinning from obstacles, which can facilitate plastic deformation severely under sufficiently high DB concentration. Such conditions can be realized under irradiation of crystals with swift particles or under sufficiently high temperatures. The models are compared with experimental data on several metals. Possible role of discrete breathers in thermally activated fracture of graphene under tensile load is discussed.

Simulation of the interaction between discrete breathers of various types in a Pt3Al crystal nanofiber

“…The frequency of soft type DBs decreases as their amplitude increases (these DBs can exist only in crystals that have a gap in the phonon spectrum; their frequency lies in the gap of the phonon spectrum; therefore, these DBs are called gap DBs), whereas hard type DBs exhibit the converse behavior (the fre quencies of these DBs may lie both in and above the gap of the phonon spectrum). DBs with soft type non linearity can be excited in biatomic crystals, for exam ple, in NaCl [11,13], Pt 3 Al [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], as well as in graphene and graphane [33][34][35]. Breathers with hard type nonlinearity exist in pure metals with FCC, BCC, and HCP structures.…”

“…Investigations related to DBs have recently reached a higher level. The results of many recent works show that DBs exist in almost all crystals [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. There is every reason to believe that DBs find application as a means to explain various physical phenomena in crystals.…”

Interaction of discrete breathers with primary lattice defects in bcc Fe

“…Whether the release of intrinsic and kinetic DB energy by scattering on natural lattice defects such as vacancies, dislocations or grain boundaries would essentially influence materials properties or not is to be studied. If indeed, the scattering of a DB results in a localized atomic excitation, equivalent to a heating of material 'in a spot', this interaction should amplify the reaction rates due to effective reduction of the underlying activation barriers, as was recently proposed in [26][27][28]. Correspondingly, a qualitative and quantitative assessment of the interaction of DBs with lattice defects is not limited to academic interest and should be done to evaluate the possible impact of the DB gas on the material properties.…”

Discrete breathers with hard and soft type of nonlinearity in 1D Morse lattices with long-range interactions

“…/ Письма о материалах 5 (1), 2015 стр. [11][12][13][14] Semenov et al / Letters on materials 5 (1), 2015 pp. 11-14 дах физических систем, включая оптические, механиче-ские, электрические, атомные и др.…”

“…В классических работах по изучению ДБ рассматри-вались модельные дискретные системы низкой размер-ности с простейшими видами ангармонизмов в меж-частичных взаимодействиях [1][2][3] и были развиты аналитические и полуаналитические методы построе-ния бризерных решений, изучены их основные свойства. В настоящее время растет число работ по исследованию ДБ в различных кристаллических материалах [4][5][6][7][8][9][10][11][12][13][14][15], что требует существенного уточнения рассматриваемых моделей.…”