Densification of W–Ni–Fe powders using laser sintering

Abstract

In this paper, Laser Sintering (LS) 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 in crease of laser power and decrease of scanning speed, higher density can be achieved. The microstructure anal ysis 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 ob served. 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.

Experimental investigation of laser-assisted powder bed fusion of Fe-Cu powder mixture

“…In this process, the component which has lower melting temperature fuses and makes an adjoin between metal powders [19,20]. It is strongly emphasized that the accuracy of a part depends on careful selection of process parameters and unsuitable selection of process parameters will lead to part distortion, balling phenomena and dross formation [1,3,18,21,22]. The effective parameters of laser sintering can be divided into three general categories: process parameters, material parameters and environmental parameters [23].…”

“…Also increasing in the number of manufactured layers causes increasing temperature if no preheating is in use [18]. Wang et al reported that the laser scanning speed and laser power are the most effective parameters on density of fabricated parts [22]. They also derived a densification model to predict density.…”

Continuum Modeling of the Densification of W-Ni-Fe during Selective Laser Sintering

“…The density is a very important quality of the finished part because it has a direct relationship to strength, weight, and integrity. Wang et al (2016) have proposed a model to predict the relative density based on the processing parameters used within the scan. They were able to conclude that the most important parameters were the scanning speed and laser powder.…”

“…Advanced functionality and complex model considerations are then described and incorporated into the final model. Next, numerous simulations were conducted using W-Ni-Fe as the powder material and the results were compared to an experiment performed by Wang et al (2016). Additionally, a second study was performed in which 316L stainless steel was as the material.…”

“…The experiment was designed such that the processing parameters matched those used in the study performed by Wang et al (2016). Initially, a series of simulations were conducted using W-Ni-Fe and were compared to the experimental results.…”