A molecular dynamics study of melting and dissociation of tungsten nanoparticles

Min Li,Jun Wang,Baoqin Fu,Qing Hou

doi:10.1063/1.4939137

Abstract

Molecular dynamics simulations were conducted to study the melting and dissociation of free tungsten nanoparticles. For the various interatomic potentials applied, the melting points of the tungsten nanoparticles increased with increasing nanoparticle diameter. Combining these results with the melting point of bulk tungsten in the experiment, the melting point of nanoparticles with diameters ranging from 4 to 12 nm could be determined. As the temperature increases, free nanoparticles are subject to dissociation phenomena. The dissociation rate was observed to follow Arrhenius behavior, and the Meyer–Neldel rule was obeyed. These results are useful in understanding the behavior of tungsten dust generated in nuclear fusion devices as well as for the preparation, formation, and application of tungsten powders.

Highlights

Metal nanoparticles exhibit unique physical and chemical properties and have considerable potential applications in aerospace alloys, electrode materials, thin films, and sintering production
Many types of particles are present in the plasma, and during the flight, the tungsten dust particles are bombarded by these particles, leading to a higher temperature and the possibility of the dust particles being crushed into smaller ones
In our work, based on the tungsten nanodust particles generated in fusion devices, we investigated the melting and dissociation of tungsten nanoparticles using molecular dynamics (MD)

Summary

Introduction

Metal nanoparticles exhibit unique physical and chemical properties and have considerable potential applications in aerospace alloys, electrode materials, thin films, and sintering production. Because of its high melting point, low sputtering yield, high density, and hardness, tungsten has been applied in many industries.[11,12] In controlled nuclear fusion reactors, such as ITER,[11] tungsten has been selected as the plasma-facing material (PFM).[13] tungsten dust particles have been observed in fusion devices, including those on the nanometer length scale. As the temperature of plasma in fusion devices is high (for example, even near the PFM, the temperature can reach up to 3000 K), these tungsten dust particles may melt. Because of the high temperature, it is difficult to directly investigate the evolution of dust particles in plasma in experiments.[14]

Methods

Results

Conclusion