Microstructure and mechanical property in diode laser melting deposited AlSi10Mg

Abstract

Laser melting deposition (LMD) has great advantages and broad development prospects in the manufacture of high-performance complex aluminum alloy components. In this paper, AlSi10Mg was deposited by 5 kW diode laser, and the effects of shielding gas flow, scanning layer thickness, scanning line spacing and powder drying on the density and mechanical properties of the deposited samples formed parts were investigated in details. The results indicated that the bulk density increased significantly with the increase of the shielding gas flow rate. Meanwhile, when the powders were dried in advance, the density could reach to the 99.5 %. The maximum tensile strength was 237.81 MPa, and the elongation was 9.88 %. The columnar dendrites were observed along the boundary line and fine dendritic structure was formed in the molten pool interior. Three phases were identified in the as-fabricated bulk, including primary α-Al, eutentic Si, and Mg₂Si. Eutentic Si distributed around the columnar α-Al with a circular shape at the fusion lines, while it was uniformly distributed in the molten pool. A small amount of Mg₂Si precipitated within the α-Al matrix, which exhibited needle-like morphology.