Dendritic Structure Characteristics of the Cu-based Laser Deposited Functionally Graded Materials

The current research is devoted to the investigation of dendritic structure parameters of the Fe-Cu system functionally graded material (FGM) created via direct energy deposition (DED) laser technology. We applied the aluminium bronze with 10% content of aluminium and the stainless steel 316L as the initial materials; using a technological installation InssTek MX-1000, we produced the FGM consisted of interchanging layers of these metals. Using the model of the fast-moving concentrated source and ellipsoid crystallization front, we estimated the crystallization rate distribution from its maximal value (observed at the center of the heat spot) to the minimal value near the crystallization front. We found out that the width of the secondary elements of the dendrites in the crystallized slab should belong to the interval 0.2 nm ... ~0.4 μm. We mentioned the subinterval 0.2 nm ... ~ 50 nm as an area of 'small dendrites', and the subinterval ~0.1 ... ~0.4 μm as an area of 'huge dendrites'. We compared the theoretical results with the experimentally measured values, obtained using the scanning electronic microscopy (SEM) images. These values were found to be in a good accordance with our calculations in the area of 'huge dendrites'.