A novel laser cladding AlMgZnCuErZr alloy: Material genetic design, strengthening andtoughening mechanisms

Aluminum alloy with high strength, toughness, and corrosion resistance is one of the new materials for laser additive manufacturing of lightweight high-speed train brake discs. However, due to the non-equilibrium solidification characteristics during the laser melting process, the commercial Al alloys with high performance and laser formability face several bottlenecks in alloy composition design and preparation. This paper employs a material genetic design method to develop a novel laser cladding Al14Mg9Zn6Cu2Mn0.5Si0.6Er0.4Zr alloy, which exhibits excellent laser formability and better strength, toughness, and corrosion resistance under an optimized laser energy density of 1157 J/mm3 . Specifically, an in-situ generated T-AlMgZnCuZrEr genetic phase with internal cell-like alpha-Al was first discovered, which significantly improves the properties of the alloy. The alloy sample demonstrates a remarkable compressive strength of 663 MPa along with a deformation of 15 %. The compressive strength and deformation product of the laser cladding sample reaches 9.9 GPa%, which is 13.44 % higher than that of the high-strength AlZnMgCu alloy prepared by other subtractive manufacturing processes. The mechanisms of matching strength-toughness and corrosion resistance of the alloy have been elucidated. This study provides a feasible material design and preparation pathway for laser additive manufacturing of highperformance and lightweight Al alloy high-speed train brake discs.