Numerical and experimental study of molten pool behaviour and defect formation in multi-material and functionally graded materials laser powder bed fusion

Laser powder bed fusion (LPBF) of multi-material and functionally graded materials (FGM) has attracted significant research interest due to its ability fabricate components with superior performance compared those manufactured single material. However, the forming mechanisms various defects remain unknown. In this paper, a DEM-CFD model was first established obtain an in-depth understanding process. It discovered that including partially melted un-melted Invar36 were embedded in lower level layer; attributed low laser absorptivity, melting point high thermal conductivity Cu10Sn powder. Inter-layer more likely occur increased layer thickness. addition, scanned track width found related equilibrium achieved among properties mixture. Process parameters optimised FGM structures without both horizontal vertical directions. Invar36/Cu10Sn samples fabricated LPBF system using different mixed contents volumetric energy densities (VEDs). By increasing VED, fewer observed between interface two processed layers, which had good agreement modelling results.