Developing a novel high-strength Al–Mg–Zn–Si alloy for laser powder bed fusion

Additively manufactured (AM) aluminium alloys have attracted increasing attention due to the great demand of prototyping, spare parts supply, short run productions and further light-weighting of vehicles. However, most of the reported AM aluminium alloys are usually modified version of commercial cast or wrought aluminium alloys. In this work, we successfully developed a new high-strength and ductile Al5Mg3Zn2Si alloy, which is designed for laser powder bed fusion (LPBF) process. The optimized relative density of 98.9% was obtained at a volumetric energy density (VED) of 129.1 J/mm3. The as-LPBFed Al5Mg3Zn2Si alloy features refined equiaxed α-Al grains and Al–Mg2Si eutectic network. In addition, the sub-micrometre sized, coherent α-Al(Fe,Mn)Si and MgZn2 dispersoids in conjunction with high number density of (Mg,Zn)-rich GP zones co-contribution to the excellent combination of mechanical properties, i.e. the ultimate tensile strength of 548 MPa, the yield strength of 403 MPa, and the elongation of 6.7%. Such a high-strength and ductile AM aluminium alloys without any addition of costly alloying elements has a great potential for automotive and aerospace applications.