Densification of W-Ni-Fe powders using laser sintering

In this paper, Laser Sintering (IS) of 90%W-7%Ni-3%Fe (wt.%) powders have been investigated, with the goal to understand the influence of final density by laser power, scanning speed, laser trace width, and the number of scanning passes. The results suggest that the laser power and scanning speed are the most important factors influencing density; the influence of trace width and number of scanning passes are not significant. With the increase of laser power and decrease of scanning speed, higher density can be achieved. The microstructure analysis indicated that the porosity changed from open porosity to closed porosity with higher laser energy input. Energy-Dispersive X-ray Spectroscopy (EDX) analysis shows that during the sintering process, W was not melted but dissolved into the Ni-Fe matrix. Contact flattening and grain accommodation of W grains have been observed. It suggests that both rearrangement and solution-reprecipitation mechanisms are responsible for the densification. The sintered density with respect to laser power and scanning speed was modeled by continuum modeling theory and compared with experimental results. (C) 2016 Elsevier Ltd. All rights reserved.