Columnar to equiaxed transition during direct metal laser sintering of AlSi10Mg alloy: Effect of building direction
Abstract
In the current study, cylindrical samples of AlSi10Mg alloy were fabricated using direct metal laser sintering (DMLS) technique in vertical and horizontal directions. The microstructure of the samples was analyzed using scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. It was observed that, by changing the building direction from vertical to horizontal, columnar to equiaxed transition (CET) occurred in the alloy. While 75% of the grains in the vertical sample were columnar, by changing the direction to horizontal, 49% of the grains evolved with columnar shape and 51% of them were equiaxed. Moreover, the texture of DMLS-AlSi10Mg alloy changed due to CET. While {001} fiber texture evolved in the vertical sample, the <001> direction tilted away from the building direction in the horizontal one. Using the fundamentals of solidification and constitutional undercooling, the solidification behavior of AlSi10Mg alloy during DMLS process was modeled. It was observed that, the determinant parameter in CET during DMLS of AlSi10Mg alloy is the angle between the nominal growth rate and direction of the growing dendrite, which is controlled by the geometry and building direction of the sample. Further TEM studies confirmed that, CET alters the shape and coherency of Si precipitates and dislocation density inside the α-Al dendrites in DMLS-AlSi10Mg alloy.
Publication Title
Additive Manufacturing
Recommended Citation
Hadadzadeh, A., Amirkhiz, B., Li, J., & Mohammadi, M. (2018). Columnar to equiaxed transition during direct metal laser sintering of AlSi10Mg alloy: Effect of building direction. Additive Manufacturing, 23, 121-131. https://doi.org/10.1016/j.addma.2018.08.001
