Microstructural evolution and characterization of AlSi10Mg alloy manufactured by selective laser melting

Abstract

Extensive investigation of the influence of the selective laser melting (SLM) process parameters on the evolution of the molten pool is of great significance to understanding microstructure control and SLM-fabricated part quality. This study focuses on the influence of the scan speed inducing the laser energy changes on the microstructural evolution, texture and phase of AlSi10Mg alloy during SLM. The microstructural evolution and characterization of the SLM-manufactured AlSi10Mg alloy were investigated by scanning electron microscope/electron backscattered diffraction (SEM/EBSD), transmission electron microscope/scanning transmission electron microscope (TEM/STEM) and X-rays diffraction (XRD). The microstructural features of the sample have shown that the primary cellular dendritic structure sizes in the coarse grain zones were about three times larger than those in fine grain zones due to the different cooling rates. Besides, the microstructure boundary contains a eutectic mixture of Al and Si while the matrix is mainly composed of α-Al. The interplanar distance between the fringes are measured as 3.84 Å and 2.86 Å corresponding to the (110) plane of Si and (110) plane of Al. On the other hand, the hardness measurement data show that the sample due to the high scan speed is larger than that of the low scan speed. Meanwhile, the (001) Al texture strength of samples in the low scan speed is stronger than those in the high scan speed. Finally, the XRD analysis reveals that no significant differences are found in the intensity of (111) α-Al, while the intensity of the (200) α-Al presents a difference because of the grain orientation and size.