Sintering of AlSi10Mg particles in direct metal laser sintering process: A molecular dynamics simulation study

The consolidation of metal powders having nano-sized particles in direct metal laser sintering process has a profound effect on the crystal structure, mechanical, and physical properties of the fabricated part. A model based on Molecular Dynamics (MD) is developed to investigate the sintering mechanism of AlSi10Mg metal powders having different size. The neck growth, shrinkage ratio, the radius of gyration, and diffusivity are calculated with respect to the sintering time, which gives the fundamental understanding of the sintering behavior of metal powders at the atomistic level. The current study reveals that solid state and liquid state diffusion takes place during the sintering of metal powders in the direct metal laser sintering process. It is observed that during sintering of nano-sized particles the interfacial atoms have higher mobility than the surface atoms, which results in higher densification of the fabricated part. The diffusivity of AlSi10Mg for an equal sized particle is 2.45 x 10(-5) m(2)/s and for unequal sized particles is 5.27 x 10(-7) m(2)/s, which confirms that the diffusion rate is faster in unequal sized particles. Also in the multicomponent alloy system, the diffusion rate is faster as compared to pure metal. These results could provide the information to optimize the processing conditions and material designs applicable to nano-sized metal powders having different compositions. Also, it is expected that the MD model will act as a foundation for the multiscale modeling of sintering phenomena in the powder bed additive manufacturing processes.