Microstructure and mechanical properties of Al-Mg-Mn-Er-Zr alloys fabricated by laser powder bed fusion

• Published in: Materials & design 2022-10, Vol.222, p.111064, Article 111064
• Main Authors: Guo, Yanwu, Wei, Wu, Shi, Wei, Zhou, Xiaorong, Wen, Shengping, Wu, Xiaolan, Gao, Kunyuan, Zhang, Dongyun, Qi, Peng, Huang, Hui, Nie, Zuoren
• Format: Article
• Language: English
• Subjects: Additive manufacturing; Aluminum alloys; Er-Zr modification; Er-Zr synergism; Hot cracking
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2022.111064

[Display omitted] •Increasing Er content could reduce crack density in Al-Mg alloy fabricated by laser powder bed fusion.•Al3Zr particles with L12 structure promote the formation of equiaxed grains and refine the grain size.•Er-Zr synergistic effect promotes the precipitation of Al3(Er,Zr) and improves the tensile properties during aging treatment.•The Al-6Mg-0.7Mn-0.4Er-1.2Zr alloy has a strength of more than 500 MPa after heat treatment and has a cost advantage. This paper centers on high-strength Al-Mg-Mn-Er-Zr alloy, which was developed through the addition of Er, a cheap rare earth element, and suitable for additive manufacturing (3D printing). The microstructure and mechanical properties of Al-Mg-Mn-Er-Zr alloy of as-built and heat treated samples have been characterized, which shows: the precipitation of Al3Zr primary phase at the boundary of molten pool promotes heterogeneous nucleation and refines the grains, which suppresses the formation of solidification cracking in Al-Mg alloy. To bring the Er-Zr synergistic effect into play during the aging heat treatment, the nano-scale precipitation phase of Al3Er that diffuses nucleation at an earlier stage promotes the precipitation of Zr, leading to the formation of Al3(Er,Zr) core-shell structure and enhancing precipitation strengthening effect. Under the combined effects of multiple strengthening mechanisms, the yield strength could reach 440 ± 3 MPa; tensile strength, 520 ± 2 MPa and elongation 15.5 ± 1.0 %.