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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Melting, Solidification and Coalescence of Metallic Particles Invoked by Laser Heating

Get access (open in a dialog) DOI: 10.1615/IHTC15.tpm.009456
pages 8633-8646

要約

This study is focused on numerical investigation of heat transport, melting, solidification and coalescence of metallic particles invoked by laser heating in application to selective laser sintering (SLS) of metal powders. The selective laser sintering is a very promising rapid manufacturing technology. This technology can be applied to fabrication of porous metal structures with high degree of control over the final microstructure and porosity. The final microstructure is governed by very complex heat, mass and momentum transport in powder bed. The metal powder is heated by local constant or pulsed irradiation from a moving laser source. The powder is sintered due to liquid-liquid contact growth during partial melting of particles retaining an unmelted solid core. The interparticle contacts are developed by capillary flow of the melt driven by high curvature gradients in the vicinity of the contact area. The densification is accompanied by mutual approaching of solid cores, growing size of liquid neck between the particles and finally by particle cooling and melt solidification. A representative case of two particles in contact is considered for investigation. The governing equations for heat transfer and flow of liquid melt are solved using boundary method. The model accounts for simultaneous heat transfer, melting during laser heating cycle and subsequent melt flow due to surface tension forces. Detailed study of the effect of process parameters on particle temperature evolution, contact growth and densification rate is conducted and discussed.