Phase analysis and microstructure characterisation of AlSi10Mg parts produced by Selective Laser Melting

Microstructural features of AlSi10Mg samples produced by Selective Laser Melting (SLM) technique were systematically characterised. The results showed that certain amount of Si dissolved in the Al matrix (face centre cubic) to form cellular-dendritic alpha-Al phase. These cells were approximated to be 500 nm. The lattice constant value was found to decrease, resulting from the solid solution of Si in aAl. Along the boundary of these cells, Mg element clusters were also detected where X-Ray diffraction and energy dispersive X-ray spectroscopy results indicated that Mg2Si dispersoid hardening phase was formed during the SLM process. In addition, the network features along the boundary of Al phase were identified to be eutectic Al/Si phase according to the transmission electron microscopy (TEM)-EDS result. Very fine grainy features of nanometric scale were observed within this phase with dimensions less than 5 nm.