مشخصات پژوهش

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.