Page 29 - MSAM-1-2

Materials Science in Additive Manufacturing Laser absorption and printability of 90W-Ni-Fe

the above discussion and results, several conclusions can
be drawn:
(i) It was discovered that the morphology of nanoparticle-
coated 90W-Ni-Fe powder prepared by different
milling conditions was different; this was attributed
to the difference in milling energy caused by different
milling parameters. Reinforced particles were
gradually dispersed uniformly with increased specific
impact energy in ball milling, but particle deformation
and breakage were more likely to occur.
(ii) Powder morphology was optimized to obtain stable
laser absorption behavior with high absorptivity in
both horizontal and vertical directions of the powder
bed. Homogeneous nanoparticle-coated 90W-Ni-Fe
Figure 14. Compressive stress-strain curve of LPBF-processed part powder with good sphericity had the best laser
fabricated by optimized nanoparticle-coated 90W-Ni-Fe powder. absorption behavior. Agglomerated nanoparticles
made laser beams reflect between nanoparticles and
A B reduced the stability of laser absorption behavior.
Deformed matrix particles weakened the multiple
reflections and lowered laser absorptivity and
penetration.
(iii) Laser absorption of nanoparticle-coated 90W-Ni-Fe
powder with different morphologies was different,
thus making their LPBF printability different.
Figure 15. Microstructures of LPBF-processed W (A) and W-Ni-Fe (B) Homogeneous nanoparticle-coated 90W-Ni-Fe
specimens. powder with good sphericity had the best LPBF
printability with a straight scanning track free of
improvement of compressive strength was attributed to balling effects, which had a good agreement with
the transformation of the microstructure from columnar modeling results.
to equiaxial grains when the Ni and Fe nanoparticles were (iv) The 90W-Ni-Fe alloys fabricated by optimized powder
added to the W matrix. As the surfaces of W particles were had the best surface quality (surface roughness of
coated with Ni and Fe, the continuous growth of W grains 7.91 μm), the highest densification level (density
was prevented and the growth of the equiaxial grains of 98%), and uniform residual stress distribution.
was promoted instead. Meanwhile, the nanoparticles Moreover, the 90W-Ni-Fe alloys had a uniform hardness
were diffused to the grain boundaries due to their strong distribution with an average value of 439.47 HV , and
1
activity, reducing the microcracks and resultant grain they had better compression properties (compressive
boundary strengthening. The microstructures directly strength of 1255.35 MPa with an elongation of 24.74%)
determined the mechanical properties of the final parts, compared with LPBF-processed pure W parts.
thereby improving the mechanical properties of LPBF- Acknowledgments
fabricated W-Ni-Fe alloys.
None.
4. Conclusion
Funding
Through numerical and experimental investigations,
this study examined the effects of nanoparticle-coated This work was supported by the Science Challenge Project
90W-Ni-Fe powder morphology on the laser absorption (No. TZ2018006-0301-02 and No. TZ2018006-0303-03),
behavior and the printing quality of LPBF. GO-RT models National Natural Science Foundation of China for Creative
th
and CFD-PM models were first established to obtain an Research Groups (Grant No. 51921003), The 15 Batch
in-depth understanding of mechanisms during LPBF of “Six Talents Peaks” Innovative Talents Team Program
fabrication of W-based alloys. Nanoparticle-coated (No. TD-GDZB-001), The Fundamental Research Funds
90W-Ni-Fe powders were prepared and corresponding for the Central Universities (NO. NC2020004), and Basic
alloys were fabricated by a self-developed device. Based on Strengthening Program (No. 2019-JCJQ-JJ-331).

Volume 1 Issue 2 (2022) 11 http://doi.org/10.18063/msam.v1i2.11