Laser sintering of Cu nanoparticles: analysis based on modified continuum-atomistic model

Abstract

This paper reports on the use of molecular dynamics simulation in conjunction with a modified two-temperature model to elucidate the dynamic behavior of copper nanoparticles (Cu-NPs) undergoing laser sintering. Simulations were conducted using seven models of Cu-NP powders to investigate the means by which particle size (SP), incident laser fluence (I0), and stacking patterns (powders comprising Cu-NPs of either one or two sizes) affect the evolution of electronic temperature (Te), lattice temperature (Tl), pressure (P), and atomic density (dAN) in Cu-NP powders under the effects of laser sintering. We also studied the evolution of sintering configurations and the radial distribution function (g(r)) of Cu-NPs. In powders comprising Cu-NPs of uniform size (2 nm $$\le$$ Sp $$\le$$ 5 nm), the apparent density (d) initially increased (i.e., the powder densified) with I0 and then decreased (i.e., the powder coarsened) with a further increase in I0. Single-size powders composed of smaller Cu-NPs (Sp = 1 nm) underwent densification followed by coarsening followed by densification. Dual-size powders comprising Cu-NPs (Sp = 1 and 3 nm) underwent coarsening almost linearly with an increase in I0, due to the fact that in this model, the incident energy was sufficient to facilitate the atomic diffusion of smaller Cu particles toward larger Cu particles.