A high Fe-containing AlSi12 alloy fabricated by laser powder bed fusion

Abstract

Copyright © 2022 The Author(s). The high Fe-containing AlSi12 alloy was processed by additive manufacturing of laser powder bed fusion (LPBF) to understand the features of microstructures and mechanical properties under as-fabricated condition. The Fe impurity was found to be beneficial for mechanical property enhancement in the LPBFed samples. The parameters including the combination of laser power of 200 W, scanning speed of 1110 mm/s, hatch spacing of 0.15 mm, layer thickness of 0.03 mm and laser volumetric energy density of 40 J/mm3 were optimized to achieve a high relative density of 99.7%. The as-LPBFed AlSi12FeMn alloy was featured by a high density of significantly refined spherical α-Al(Fe,Mn)Si phase (10–50 nm), which was coherent with the Al matrix. Meanwhile, the as-LPBFed AlSi12FeMn alloy can deliver superior mechanical properties including the yield strength of 305 MPa, the ultimate tensile strength of 485 MPa and the fracture strain of 6.1%. The improved mechanical properties are attributed to synergistic strengthening mechanisms, including solid solution strengthening, grain boundary strengthening and precipitation strengthening. Moreover, the formation of high-density stacking faults (SFs) and Lomer-Cottrell locks (LCs) in localized regions can also offer strengthening in the as-LPBFed AlSi12FeMn alloy.