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<p>Gas tungsten arc-based wire arc additive manufacturing (GTA-WAAM) has attracted increasing attention for the fabrication of large-scale magnesium alloy structural components. However, studies on rare-earth-strengthened cast magnesium alloys, such as EV31A, remain scarce. In this work, a single-pass multi-layer thin-walled Mg–3Nd–1.3Gd alloy was successfully fabricated using the GTA-WAAM process, and its microstructural evolution and mechanical properties were systematically investigated. The deposited microstructure is predominantly composed of equiaxed grains. During the remelting stage, the original precipitates partially dissolve into the matrix, while the subsequent thermal cycling promotes their re-precipitation and coarsening, resulting in the formation of dispersed strengthening phases. The as-cast Mg–3Nd–1.3Gd alloy exhibits a certain degree of mechanical anisotropy, with an ultimate tensile strength of approximately 103 ± 2.1&#xa0;MPa, a yield strength of about 92 ± 5.6&#xa0;MPa, and an elongation of 2.8 ± 0.53 pct. Reduced mechanical anisotropy after heat treatment, although a certain directional dependence in elongation is still retained. The heat-treated samples achieve ultimate tensile strengths of 248.1 ± 1.4 and 232.9 ± 11.2&#xa0;MPa in the horizontal and vertical directions, respectively, with corresponding elongations of 20.8 ± 4.6 and 15.0 ± 6.5 pct, which are markedly superior to those of the as-cast alloy. In addition, a relatively uniform microhardness distribution with an average value of 87.76&#xa0;HV<sub>0.2</sub> is obtained, indicating good microstructural homogeneity and mechanical stability. These results demonstrate that GTA-WAAM is a promising approach for fabricating high-performance EV31A magnesium alloy components and provides a viable pathway for the additive manufacturing of rare-earth-strengthened magnesium alloys.</p>

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Wire Arc Additive Manufacturing of Mg–3Nd–1.3Gd Alloy: Microstructural Evolution and Mechanical Enhancement Induced by Intrinsic Heat Treatment

  • 期刊论文

  • 发表日期：

    2026年7月24日

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  • Hongbin Dai,
  • Han Jia,
  • Chaoxiang Chang,
  • Guanlin Feng

摘要

Gas tungsten arc-based wire arc additive manufacturing (GTA-WAAM) has attracted increasing attention for the fabrication of large-scale magnesium alloy structural components. However, studies on rare-earth-strengthened cast magnesium alloys, such as EV31A, remain scarce. In this work, a single-pass multi-layer thin-walled Mg–3Nd–1.3Gd alloy was successfully fabricated using the GTA-WAAM process, and its microstructural evolution and mechanical properties were systematically investigated. The deposited microstructure is predominantly composed of equiaxed grains. During the remelting stage, the original precipitates partially dissolve into the matrix, while the subsequent thermal cycling promotes their re-precipitation and coarsening, resulting in the formation of dispersed strengthening phases. The as-cast Mg–3Nd–1.3Gd alloy exhibits a certain degree of mechanical anisotropy, with an ultimate tensile strength of approximately 103 ± 2.1 MPa, a yield strength of about 92 ± 5.6 MPa, and an elongation of 2.8 ± 0.53 pct. Reduced mechanical anisotropy after heat treatment, although a certain directional dependence in elongation is still retained. The heat-treated samples achieve ultimate tensile strengths of 248.1 ± 1.4 and 232.9 ± 11.2 MPa in the horizontal and vertical directions, respectively, with corresponding elongations of 20.8 ± 4.6 and 15.0 ± 6.5 pct, which are markedly superior to those of the as-cast alloy. In addition, a relatively uniform microhardness distribution with an average value of 87.76 HV0.2 is obtained, indicating good microstructural homogeneity and mechanical stability. These results demonstrate that GTA-WAAM is a promising approach for fabricating high-performance EV31A magnesium alloy components and provides a viable pathway for the additive manufacturing of rare-earth-strengthened magnesium alloys.