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Abstract
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The Ni-based superalloy is one of the important high temperature structural materials used for the
modern aero engines and gas turbines. In order to improve the mechanical properties of additively
manufactured Ni-based superalloys, deeply understanding of the selective laser melting
(SLM) process and controlling its technological parameter are of great significance. In present
work, we regulate the process parameters (scanning speed and laser power), and then study their
impact on the thermal behavior, molten pool configuration, and microstructural evolution of the
SLM Ni-based alloys using the finite element simulation and molecular dynamics simulation. The
results show that the maximum cooling rate and temperature gradient of the molten pools increase
significantly with the increasing laser power, but they slightly reduce with the increasing
scanning speed. The molecular dynamics simulations reveal the atomic-scale crystallization.
during the melting process of Ni-based superalloys. The SLM alloys present the high surface
quality and structure. Meanwhile, the nanoscale Cr clusters would be formed during the melting
process. This segregation phenomenon makes the connection between processing parameters,
microstructure and properties established. Our investigation sheds new insights into the solidification
mechanism in SLM Ni-based superalloys at a nanoscale, which is expected to be helpful
for the preparation of additive manufacturing materials with extremely enhanced mechanical
properties.
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