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

Liao

et al. 2023

Mater. Res. Express

Selective laser melting (SLM) is used extensively in the manufacture of components for both production and domestic applications. However, the lack of fusion pores is one of the most common defects in the SLM process, affecting the performance and life of the part and hindering the development of the SLM process. Meanwhile, the defects are particularly sensitive to changes in SLM process parameters. The micro-selective laser melting (μ-SLM) model was established by molecular dynamics simulation, and the lack of fusion pores in the melt pool was analyzed by a multifunctional wavefunction analyzer to understand the difference of the porosities under different processes. The results show that both laser power and scanning speed can prolong the existence time of the melt pool by changing the input energy density. The melted powder has more time to fill the lack of fusion pores, thus reducing the porosity. The larger scanning spacing hinders the combination of adjacent melt pools, leading to an increase in porosity. Reducing scanning spacing will lead to sintering or remelting, thus improving the bonding quality of adjacent melt pools and effectively reducing porosity.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of porosity in lack of fusion pores in selective laser melting using the wavefunction

Liao

et al. 2023

Mater. Res. Express

“…The overall system was demonstrated using a hybrid pair style with distinguishable interatomic potentials. Nandy et al [ 34 ] used MD simulations to analyze AlSi10Mg particles using a combination of the embedded atomic method (EAM) and the Tersoff and Lennard–Jones (LJ) potentials. The EAM potential was used to describe the Al–Al [ 35 ] and Mg–Mg [ 36 ] pair potentials, and the total energy E of N atoms can be expressed as follows [ 35 , 36 , 37 ]:

where F i represents the embedding energy function of an atom i for the electron density function, and ρ i and ϕ ij represents the repulsive pair potential between atoms i and j with a distance r ij .…”

Section: Molecular Dynamics (Md) Simulationmentioning

confidence: 99%

Molecular Dynamics Study on Crack Propagation in Al Containing Mg–Si Clusters Formed during Natural Aging

2023

The crack propagation behavior of Al containing Mg–Si clusters is investigated using molecular dynamics (MD) simulations to demonstrate the relationship between the natural aging time in Al–Si–Mg alloys and ductility. Experimental results show that the elongation at failure decreases with natural aging. There are few studies on the relationship between natural aging and ductility because of the difficult observation of Mg–Si clusters. To solve the difficulty, cracked Al containing Mg–Si clusters of varying sizes are assumed for the MD simulations. A larger Mg–Si cluster in Al results in earlier crack opening and dislocation emission. Moreover, as the Mg–Si cluster size increases, the stress near the crack tip becomes more concentrated. This causes rapid crack propagation, a similar effect to that of crack tip sharpening. As a result of long-term natural aging, the cracks expand rapidly. The influence of geometry is also investigated. Crack lengthening and thickness reduction negatively impact the fracture toughness, with the former having a larger impact than the latter. Although there are several discrepancies in the practical deformation conditions, the simulation results can help to more thoroughly understand natural aging in Al–Si–Mg alloys.

“…In the implemented model, linear interpolation is used between the material parameters for a given temperature. Based on Nandy et al [16], T Sint = 527 • C and T L = 596 • C were chosen. In addition, perfect thermal contact is assumed between the powder bed and the substrate, as well as between the powder bed or substrate and the overprinted temperature-unstable material.…”

Section: Process Simulation Pbf-lb/mmentioning

confidence: 99%

Thermal Modeling of Laser Powder Bed Fusion during Printing on Temperature-Unstable Materials Considering Local Sintering

Frölich

Kärger

2022

KEM

The integration of local metal structures into polymer components using Laser Powder Bed Fusion (PBF-LB/M) offers great potential regarding multifunctional lightweight structures. However, such process hybridization involves huge challenges. In order to reduce the temperature input into the less temperature-resistant materials, the use of lower laser powers in the interfacial region is essential. The resulting local sintering of the metal powder affects the thermal properties in the interfacial region, leading to a change in heat dissipation in the temperature-unstable material. A modeling approach oriented to selective laser sintering is presented for predicting the degree of sintering and associated thermal properties in the context of PBF-LB/M process simulation.