Three-Dimensional Sintering of Two-Component Metal Powders With Stationary and Moving Laser Beams

Abstract

Melting and resolidification of a mixture of two metal powders with significantly different melting points under irradiation of a stationary or a moving Gaussian laser beam were investigated numerically and experimentally. The liquid motion driven by capillary and gravity forces as well as the shrinkage of the powder bed caused by the overall density change were taken into account in the physical model. The liquid flow was formulated by using Darcy’s law, and the energy equation was given using a temperature transforming model. Prediction were compared with experimental results obtained with nickel braze and AISI 1018 steel powder. The effects of laser properties and the scanning velocity on the laser sintering process were also investigated. An empirical correlation that can be used to predict the cross-sectional area of the heat affected zone is proposed. [S0022-1481(00)70201-5]

Selective laser sintering: A qualitative and objective approach

“…43,44,78 When mixing two metal powders with signifi cantly different melting points, the liquid fl ow driven by capillary and gravity forces and the solid particle velocity induced by shrinkage of the powder bed must be taken into account. 79 A different modeling approach (i.e., ray tracing modeling) has also been employed with and without fi nite element simulation. This approach is based on the geometrical simulation of the impingement, refl ection, and absorption of a large number of laser rays into the powder bed.…”

Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

“…Melting and resolidification of a subcooled semi-infinite two-component metal powder bed with a moving Gaussian heat source was simulated by Zhang et al [12]. The threedimensional sintering process of two-component metal powder with stationary and moving laser beams was simulated by Zhang et al [13].…”

Modeling of thermal processes in laser sintering of reactive powder compositions

“…We note that, even in a one-component powder medium, we always have a variation in the particle size and the early melting of the finely divided part of the fraction is actually analogous to liquid-phase sintering. We know of numerous attempts at modeling the SLS process by the finiteelement method and within the framework of the semiclassical approach in the literature [8][9][10].The present work seeks to construct and investigate a two-dimensional model theoretical description of the SLS of such SHS layers. It should be emphasized that, unlike the SHS macrokinetics, our interest was predominantly with the conditions of preservation of the controllability of the process in question due to the corresponding modifications of the laser-source parameters (the power and rate of scanning of the laser action, the spot diameter) rather than the special properties of reaching quasistationary model regimes (their stability, self-propagation velocity, etc.)…”

“…(10) Numerical Analysis. The system of equations (8) was solved based on difference schemes by the well-known method of variable directions with the use of the marching method.…”

“…We note that, even in a one-component powder medium, we always have a variation in the particle size and the early melting of the finely divided part of the fraction is actually analogous to liquid-phase sintering. We know of numerous attempts at modeling the SLS process by the finiteelement method and within the framework of the semiclassical approach in the literature [8][9][10].…”