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Start Over Author "Wang, Yaodong" Publication Type Academic Journals
457 results on '"Wang, Yaodong"'

48. Three-Dimensional Simulation Research on Discharge Characteristics of Inductively Coupled Plasma

Author

Guo Xu, Li Yinghui, Qiu Chenlin, Chang Yipeng, Wang Yaodong

Subjects
inductively coupled plasma, fluid mechanics, discharge characteristics, finite element method, radar echo, stealth, aircraft, Motor vehicles. Aeronautics. Astronautics, TL1-4050
Abstract

Aiming at the discharge problem of inductively coupled plasma (ICP), a closed wave-transmitting cavi-ty configuration is designed, the fluid mechanics model of ICP is established, and the multi physical simulation software COMSOL is used for three-dimensional simulation research. The variation laws of typical parameters such as electron density, electron temperature and plasma potential with time in the discharge process are analyzed. On this basis, the power of radio frequency power supply, the air pressure in the cavity and other conditions are changed to obtain the parameter range and spatial gradient distribution of ICP. The results show that the discharge power mainly affects the numerical range of plasma parameters, and the change of air pressure has an effect on the numerical value and spatial distribution of plasma parameters. When the power of radio frequency power supply increases from 100 W to 300 W, the peak electron density increases from 2.54×1017 m-3 to 5.68×1017 m-3, and the electric potential induced in the heating zone and the corresponding electron temperature decrease slightly after the reaction is stable. Increasing the air pressure in the cavity within a certain range will significantly increase the electron density. The air pressure increases from 10 Pa to 30 Pa, and the electron density increases from 9.12×1017 m-3 to 3.62×1018 m-3. However, the uniformity of plasma parameter distribution will deteriorate if the air pressure is too high.

Published
2022
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50. Atomic insights into the effect of rapid heating pretreatment on the mechanical stability of ⟨100⟩ symmetrical tilt GBs in nanocrystalline materials.

Author

Wang, Yaodong, Li, Chunpeng, Li, Jiejie, and Li, Jianjun

Subjects
*SHEAR (Mechanics), *THERMAL instability, *MECHANICAL alloying, *MOLECULAR dynamics, *SHEARING force, *COPPER
Abstract

Nanograined materials possess ultrahigh strength, while their processing and technological applications are constrained by inherent thermal and mechanical instability. Existing experiments show that the stability of Cu nanograins can be enhanced by performing a rapid heating pretreatment that reduces the grain boundary (GB) energy by changing the GB structure. The variation in the GB structure inevitably affects the migration mechanism of GBs. However, the effect of the pretreatment-induced variation in migration mechanisms on stability remains unclear. Here, the shear deformation of a series of ⟨ 100 ⟩ symmetrical tilt GBs after rapid heating pretreatment is systematically investigated by molecular dynamics simulations. The simulations of unheated GBs are also included for comparison. Our results show that the rapid heating pretreatment does not improve the mechanical stability of GBs with tilt angles larger than 36.87° but rather enhances the mechanical stability of those with tilt angles less than 36.87° by the transformation of migration behavior from the normal ⟨ 110 ⟩ mode to (i) a ⟨ 100 ⟩ mode; (ii) an inhomogeneous mixed one that reconciles the ⟨ 110 ⟩ and ⟨ 100 ⟩ modes; and (iii) an inhomogeneous ⟨ 110 ⟩ mode. The former leads to an increase in the critical shear stress that is required to initiate the migration, whereas the latter two result in a decrease in the migration distance. The variation in the GB migration mechanism is attributed to the change in the GB structure from an ordered kite structure to a disordered one. The research gives an atomic insight into the stabilizing mechanism of nanocrystalline materials with rapid heating pretreatment. [ABSTRACT FROM AUTHOR]

Published
2023
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