Page 22 - MSAM-1-2

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

A B

Figure 2. Mechanism of LPBF processing (A) and the algorithmically generated powder bed (B).

A B A B

C D

C D

Figure 3. Fresnel formulae for calculating absorptivity for S and P
polarization of W (A), Ni (B), and Fe (C), and the powder bed with
indices defined (D). Figure 4. Schematic diagram of integrating sphere (A), GO-RT model
with Gaussian laser source and spherical analytical surface (B), and
complicated interaction between the powder bed and laser beam
2.4. Establishment of CFD-PM models (C and D).
Geometric information was also imported into the
computational fluid dynamics simulation software where T is the surrounding temperature, h is the heat
c
0
FLUENT. During the construction of the CFD-PM model, conduction coefficient, σ is the Stefan-Boltzmann constant,
the laser energy conversion factor of the volumetric and ε is the emissivity. The side and bottom boundaries were
[14]
Gaussian heat source was set concerning simulation and settled as insulation boundaries . More modeling details
experimental results. The modified heat flow distribution of were set concerning existing reports to illustrate the effect
the moving Gaussian heat source can be described as [14,23,24] : of nanoparticle-coated 90W-Ni-Fe powder morphology on
the non-uniform melting behavior during LPBF [8,13,14,22-25] .
2
6 PA 9( x y )
2
q exp( ) (5) 3. Results and discussion
2
2
3
RH ( 11/ e ) R log( H z/)
3.1. Effects of nanoparticle-coated 90W-Ni-Fe powder
where P is the laser power, R is the spot radius, and is morphologies on the laser absorption behavior
the laser heat source depth. Considering that most of the
heat was conducted by the powder bed and solidification Before establishing models, the morphologies of
layer, the boundary conditions were described as : nanoparticle-coated 90W-Ni-Fe powder were observed.
[24]
Energy input during the milling process was different
T under different milling conditions, thus producing
4
K + (- )+hT T T ( 4 T ) =q (6)
n c 0 0 nanoparticle-coated 90W-Ni-Fe powder with different
Volume 1 Issue 2 (2022) 4 http://doi.org/10.18063/msam.v1i2.11