Effect of Sc/Zr on the Mechanical and Corrosion Properties of A356 Aluminum Alloy

JIANG Yangfan; ZENG Xianghao; HE Guanqiang; CHEN Yuqiang; HE Zhengmao; LU Dingding

doi:10.3969/j.issn.1674-6457.2026.07.009

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (7) : 92-106. DOI: 10.3969/j.issn.1674-6457.2026.07.009

Light Alloy Forming

Effect of Sc/Zr on the Mechanical and Corrosion Properties of A356 Aluminum Alloy

JIANG Yangfan¹, ZENG Xianghao², HE Guanqiang², CHEN Yuqiang^3,4,*, HE Zhengmao³, LU Dingding³

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Abstract

The work aims to elucidate the synergistic regulation mechanisms of Sc/Zr composite microalloying on the microstructure, mechanical properties, and corrosion resistance of A356 aluminum alloy, thereby providing a theoretical basis for the composition design of high-performance cast aluminum alloys and the control of microstructure during precision forming. Experimental alloys were prepared by adjusting the Sc addition level while keeping the Zr content constant (approximately 0.05wt.%). Combined with the T6 heat treatment process, OM, SEM, and EDS were employed to thoroughly analyze the microstructural evolution of α-Al grains, eutectic Si phases, and Al₃(Sc,Zr) nano-precipitates. Furthermore, the alloy's hardness aging behavior at 180 ℃, strength-to-ductility ratio, and neutral salt spray corrosion behavior were systematically evaluated. All experimental alloys reached their peak hardness after 10 h of aging at 180 ℃, with the alloy having a Sc/Zr ratio of 1∶1 exhibiting the optimal balance of strength and ductility. Although increasing the Sc content could significantly refine the α-Al grains to approximately 80.9 μm, an excess of Sc led to coarsening of the Al₃(Sc, Zr) precipitation phase and severe compositional segregation, resulting in reduced aging stability and significantly increased susceptibility to intergranular corrosion. Under salt spray corrosion conditions, the alloy's strength was reduced due to corrosion damage. However, increasing the Sc content refined the microstructure, reduced the tendency for localized pitting corrosion, and suppressed microcrack initiation, resulting in a significant increase in the alloy's ductility. The synergistic effects of grain refinement and precipitation hardening through Sc/Zr can substantially improve the comprehensive properties of A356 alloy, and it has been established that a 1∶1 Sc/Zr ratio is the optimal microalloying design for achieving microstructural refinement and performance enhancement.

Key words

A356 aluminum alloy / Sc/Zr microalloying / precipitated phase / mechanical properties / corrosion resistance

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JIANG Yangfan, ZENG Xianghao, HE Guanqiang, CHEN Yuqiang, HE Zhengmao, LU Dingding. Effect of Sc/Zr on the Mechanical and Corrosion Properties of A356 Aluminum Alloy[J]. Journal of Netshape Forming Engineering. 2026, 18(7): 92-106 https://doi.org/10.3969/j.issn.1674-6457.2026.07.009

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Funding

National Key R&D Program (2022YFB4300105); General Program of the National Natural Science Foundation (52475346); Hunan Provincial Natural Science Foundation (2025JJ70085); Hunan Provincial Science and Technology Innovation Program (2025RC4011)