Evolution of a Gradient Microstructure in Direct Metal Laser Sintered AlSi10Mg

Unique and ultrafine microstructures are achieved through metal powder bed fusion additive manufacturing (AM) processes. However, a gradient in the microstructure through the height of tall-enough samples can be observed due to different cooling rates and heating-cooling cycles experienced by different locations. In the current study, a vertically built sample of AlSi10Mg with a rectangular cross section was manufactured through direct metal laser sintering (DMLS) process. The microstructure was studied at the bottom and top of the sample. From the bottom to the top of the DMLS-AlSi10Mg sample, fewer heating-cooling cycles were experienced by the material. Moreover, the cooling rate was different due to change of the thermal boundaries and cooling conditions. The microstructure of the DMLS-AlSi10Mg was analyzed using multi-scale characterization techniques including EBSD and APT. The microstructure characteristics were correlated to the solidification conditions experienced by the material.