In this work, a 2D axisymmetric model of gas atomization at unsteady state that accounts for break-up and solidification is used to simulate laser melting of gas atomized powder. With an optimal nozzle width of 0.6-1 mm and a nozzle angle of 30-32°, the yield of fine 15-45 μm stainless steel powder, suitable for selective laser melting, is shown to increase from 20% to 35%. The effect of laser power on the melting channel width, microstructure, and mechanical properties of the sample is also investigated.

This study compares the microstructure of Al 2 O 3 coatings produced by detonation gun spraying (DGS) and laser stereolithography (SLA). The SLA samples mostly consisted of alumina and voids, while the DGS-deposited alumina contained additional features such as splats, pores, cracks, and boundaries. DGS deposits were also denser with about 3% porosity compared to 8% porosity in the SLA samples. EDS analysis showed that both coatings contained only aluminum and oxygen, although additional carbon was detected in the SLA samples, indicating the presence of residual binder (resin based) material. XRD analysis revealed a mixture of α and γ-Al 2 O 3 phases in the DGS coatings, but no phase change in the SLA samples.

Despite the wide application of powder metallurgy in the field of additive manufacturing, a general understanding of the spreadability of powder particles in electron beam powder bed fusion (EB-PBF) is lacking. This paper presents the results of a literature review on particle flowability and spreading in additive processes. Different flowability tests are described and spreading mechanisms for different powder-bed processes are reviewed. A technique is proposed to study spreadability in which a single layer of powder is ‘frozen’ in the as-spread condition by contact sintering and then characterized using white-light interferometry. A standard method to calculate powder-bed density is defined based on this approach, and correlations between density, packing factor, and flowability are established.