Reduction of longitudinal ultrasonic oscillations in NaClO<sub>3</sub> crystals

Soboleva, E. G.; Igisheva, AL; Krit, T. B.

doi:10.1088/1757-899x/91/1/012032

Cited by 3 publications

(2 citation statements)

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“…In addition, alloying elements which atomic sizes differ significantly from that of Al, such as Mg and Fe, can create high stress concentrations around them that promote void formation along GBs. Moreover, as was mentioned earlier, during deformation, GB segregation can influence GBS and accommodation mechanisms that characterize plastic deformation of grains without void nucleation [52].…”

Section: Discussionmentioning

confidence: 77%

Plastic and fracture behaviour of nanocrystalline binary Al alloys with grain boundary segregation

Babicheva¹,

Stolyarov²,

Zhou³

2017

LoM

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The paper studies the stress-strain and fracture behaviour of nanocrystalline (NC) pure Al and NC binary Al-X alloys (X can be Fe, Co, Ti, Mg or Pb) with grain boundary (GB) segregation during their tensile deformation at room temperature via molecular dynamics simulation. The computational cell used for the modeling contains nano-sized grains of Al majority of which has the high-angle type GBs. The binary alloys were obtained through the substitution of Al atoms in GBs by atoms of the alloying elements. Stress-strain curves of the considered materials were calculated, and their microstructure evolution was analyzed. It was found that GB segregations can significantly alter the deformation behaviour of NC Al. The NC pure Al and two alloys, Al with Fe and Al with Mg, undergo the intergranular fracture which is noticeable already at ~8 % strain, while the other alloys do not demonstrate any failure process up to 40 % deformation. The main crack growth mechanism is the formation of nano-voids at GBs and triple junctions followed by their coalescence at higher applied stresses. The obtained results demonstrate that GB segregation of Co can have a positive effect on both plasticity and strength of NC Al, and Ti atoms in GBs can result in its improved ductility.

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Section: Discussionmentioning

confidence: 77%

Plastic and fracture behaviour of nanocrystalline binary Al alloys with grain boundary segregation

Babicheva¹,

Stolyarov²,

Zhou³

2017

LoM

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“…In the future studies it would be interesting to check if DBs can change macroscopic properties of crystals [X,Y] [25,26]. …”

Section: Discussionmentioning

confidence: 99%

Simulation of energy transport in crystal with NaCl structure assisted by discrete breathers

Семенов¹,

Bebikhov²,

Kistanov³

2017

LoM

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Discrete breather (DB) is a spatially localized vibrational mode of large amplitude with vibration frequency outside the phonon band of the crystal. DB frequency can leave phonon spectrum due to the anharmonicity of interatomic bonds owing to the fact that the frequency of a nonlinear oscillator is amplitude dependent. In the case of soft (hard) anharmonicity the nonlinear oscillator frequency decreases (increases) with amplitude. Crystals having a gap in the phonon spectrum can, in principle, support the so-called gap DBs, i.e., DBs with frequencies within the gap. The alkali halide NaI crystal possesses a wide gap in the phonon spectrum and the existence of gap DBs in this crystal has been shown by Kiselev and Sievers with the use of the molecular dynamics method. Later on, several experimental works have been undertaken to support the results of the numerical study and also the possibility of energy exchange between two closely positioned DBs was shown by atomistic simulations. In the present study the energy exchange between DBs in larger clusters is simulated by molecular dynamics. It is shown that the energy initially given to the DB cluster stays in the localized form for a long time (hundreds of DB oscillation periods) even though the energy can travel from one lattice site to another and even polarization of DBs can change. These results contribute to our better understanding of the mechanism of energy localization and transport in crystals.Keywords: discrete breather, intrinsic localized mode, phonon spectrum, lattice dynamics, nonlinear dynamics, alkali halide crystal, NaCl structure. Моделирование процесса переноса энергии в кристалле NaCl с помощью дискретных бризеровСеменов А. С. Дискретный бризер (ДБ) представляет собой пространственно локализованную колебательную моду большой ам-плитуды с частотой колебаний вне фононного спектра кристалла. Частота ДБ может выходить из фононного спектра за счет ангармонизма межатомных связей вследствие того, что частота нелинейного осциллятора зависит от амплиту-ды. В случае мягкого (жесткого) ангармонизма частота нелинейного осциллятора уменьшается (увеличивается) с ро-стом амплитуды. Кристаллы, имеющие щель в фононном спектре, могут, в принципе, поддерживать так называемые щелевые ДБ, то есть ДБ с частотами в щели фононного спектра. Щелочно-галоидный кристалл NaI обладает широкой щелью в фононном спектре за счет значительной разницы атомных масс анионов и катионов (атом натрия в 5,5 раз легче атома йода). Существование щелевых ДВ в этом кристалле было показано Киселевым и Сиверсом с использова-нием метода молекулярной динамики. Позже было проведено несколько экспериментальных работ, чтобы подтвердить результаты численного исследования. Кроме того методом молекулярной динамики была показана возможность об-мена энергией между двумя близко расположенными ДБ. В настоящей работе энергетический обмен между ДБ в более крупных кластерах моделируется методом молекулярной динамики. Показано, что энергия, первоначально переданная кластеру ДБ, остается в локализованном виде...

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The Study of Complex (Ti, Zr, Cs) Nanopowder Influencing the Effective Ionization Potential of Arc Discharge When Mma Welding

Sapozhkov

Burakova

2016

IOP Conf. Ser.: Mater. Sci. Eng.

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Reduction of longitudinal ultrasonic oscillations in NaClO₃ crystals

Cited by 3 publications

References 2 publications

Plastic and fracture behaviour of nanocrystalline binary Al alloys with grain boundary segregation

Plastic and fracture behaviour of nanocrystalline binary Al alloys with grain boundary segregation

Simulation of energy transport in crystal with NaCl structure assisted by discrete breathers

The Study of Complex (Ti, Zr, Cs) Nanopowder Influencing the Effective Ionization Potential of Arc Discharge When Mma Welding

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Reduction of longitudinal ultrasonic oscillations in NaClO3 crystals

Cited by 3 publications

References 2 publications

Plastic and fracture behaviour of nanocrystalline binary Al alloys with grain boundary segregation

Plastic and fracture behaviour of nanocrystalline binary Al alloys with grain boundary segregation

Simulation of energy transport in crystal with NaCl structure assisted by discrete breathers

The Study of Complex (Ti, Zr, Cs) Nanopowder Influencing the Effective Ionization Potential of Arc Discharge When Mma Welding

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Reduction of longitudinal ultrasonic oscillations in NaClO₃ crystals