Construction of an n-Body Potential for Revealing the Atomic Mechanism for Direct Alloying of Immiscible Tungsten and Copper

Abstract

W-Cu laminated composites are critical materials used to construct nuclear fusion reactors, and it is very important to obtain direct alloying between W and Cu at the W/Cu interfaces of the composites. Our previous experimental studies showed that it is possible to overcome the immiscibility between W and Cu and obtain direct alloying when the alloying temperature is close to the melting point of Cu. Because the W-Cu interatomic potentials published thus far cannot accurately reproduce the alloying behaviors of immiscible W and Cu, an interatomic potential suitable for the W-Cu system has been constructed in the present study. Based on this potential, direct alloying between W and Cu at high temperature has been verified, and the corresponding diffusion mechanism has been studied, through molecular dynamics (MD) simulations. The results indicate that the formation of an amorphous Cu layer at the W/Cu interface plays a critical role in alloying because it allows Cu atoms to diffuse into W. The simulation results for direct alloying between W and Cu can be verified by experimental results and transmission electron microscopy observations. This indicates that the constructed W-Cu potential can correctly model the high-temperature performance of the W-Cu system and the diffusion mechanism of direct alloying between W and Cu.

Multi-scale simulations of the mechanical behaviors of the W-Cu joint interface with a diffusion layer

“…Zeng et al [19] and Kai Wang et al [22] is adopted for molecular dynamics simulations. The Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) is employed for the all MD simulations, while the visualization of results is performed using the Open Visualization Tool (OVITO).…”

“…The F-S potential expression used in the simulations is given by: , , , , c c c c c A and B are the potential parameters to be fitted. Zeng et al [19] have successfully fitted these parameters, tested the accuracy of the potential in various ways and compared it with existing potentials [23] [24], which show significant advantages in terms of reflecting both monomeric properties and interfacial diffusion phenomena. Therefore, the potential developed by Zeng et al [19] was used for the molecular dynamics simulations.…”

“…In this study, the W-Cu potential developed by Zeng et al [19] is selected for molecular dynamics simulations because it accurately reflects the properties of pure copper, pure tungsten, nonequilibrium phases and atomic diffusion behaviors during the W-Cu alloying process. A model of the W-Cu interface with a diffusion layer is developed to investigate and simulate the mechanical behavior under mode-I and mode-II loading, and compare it to a model without the diffusion layer in order to investigate the effect of the diffusion layer on the mechanical behavior of the W-Cu interface.…”

Mass transport and thermal properties of liquid (melting to boiling point) tungsten: a molecular dynamics simulations

“…Among them due to its high melting temperature (3680-3695 K), high thermal conductivity, and low sputtering erosion, tungsten (W) is a suitable element for the plasma-facing materials in thermonuclear fusion reactors [8][9][10][11][12]. Also, its composites, e.g., W-Cu, are used in microelectronic materials and packaging materials [13][14][15][16]. Tungsten-Formulated Grease; viz, EMX-7320 [17,18], exploits the viscous nature of liquid tungsten as a lubricant, which has replaced the traditional grease in industrial usages by a large amount.…”