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<p>As a widely used high-strength aluminum alloy in aerospace, 2A12 faces challenges in conventional fusion welding due to its susceptibility to hot cracking. Diffusion bonding has emerged as a promising technique to achieve good joints while preserving mechanical properties. Molecular dynamics (MD) simulations and vacuum diffusion experiments were employed to study the diffusion behavior of Ag interlayers in 2A12 aluminum alloy bonding. An MD model for the Ag(111)/Al(111) interface was developed. At 793&#xa0;K, Al atoms exhibited a significantly higher diffusion coefficient toward Ag (0.47&#xa0;Å<sup>2</sup>/ps) than Ag toward Al (0.003&#xa0;Å<sup>2</sup>/ps), demonstrating their dominant role in the diffusion process<b>.</b> The interfacial microstructure of the vacuum-brazed joint was examined using EPMA and SEM<b>.</b> Results indicated that intermediate phases preferentially formed on the Ag side. The bonded interface exhibited a continuous distribution of Al<sub>2</sub>Ag intermetallic compounds interspersed with Ag<sub>2</sub>Al phases. The combined MD simulation and experimental results demonstrated that Al atoms primarily contribute to surface diffusion at the interface, whereas Ag atoms facilitate long-range penetration through grain boundary diffusion. Under the parameters obtained from experiments (783&#xa0;K, 5&#xa0;MPa, and 60&#xa0;min)<b>,</b> the diffusion bonded joint achieved a maximum shear strength of 111.7&#xa0;MPa. It promotes the formation of metallurgical bonding layers and inhibits brittle Ag<sub>2</sub>Al phase coarsening. The present study innovatively realizes the theoretical–experimental validation of the diffusion behaviors across the scales and offers a theoretical foundation for the optimization of the diffusion joining process of aluminum alloys.</p> Graphical abstract <p></p>

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Experimental study and molecular dynamics simulation of 2A12 aluminum alloy diffusion bonded joint with Ag interlayer

  • 期刊论文

  • 发表日期：

    2025年9月2日

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  • Chenjun Guo,
  • Yinyin Pei,
  • Yixiang Sun,
  • Liangliang Zhang,
  • Yuanxun Shen,
  • Peng Guo,
  • Pan Liu,
  • Ruilin Qiao,
  • Chao Jiang,
  • Qiang Zhang

摘要

As a widely used high-strength aluminum alloy in aerospace, 2A12 faces challenges in conventional fusion welding due to its susceptibility to hot cracking. Diffusion bonding has emerged as a promising technique to achieve good joints while preserving mechanical properties. Molecular dynamics (MD) simulations and vacuum diffusion experiments were employed to study the diffusion behavior of Ag interlayers in 2A12 aluminum alloy bonding. An MD model for the Ag(111)/Al(111) interface was developed. At 793 K, Al atoms exhibited a significantly higher diffusion coefficient toward Ag (0.47 Å2/ps) than Ag toward Al (0.003 Å2/ps), demonstrating their dominant role in the diffusion process. The interfacial microstructure of the vacuum-brazed joint was examined using EPMA and SEM. Results indicated that intermediate phases preferentially formed on the Ag side. The bonded interface exhibited a continuous distribution of Al2Ag intermetallic compounds interspersed with Ag2Al phases. The combined MD simulation and experimental results demonstrated that Al atoms primarily contribute to surface diffusion at the interface, whereas Ag atoms facilitate long-range penetration through grain boundary diffusion. Under the parameters obtained from experiments (783 K, 5 MPa, and 60 min), the diffusion bonded joint achieved a maximum shear strength of 111.7 MPa. It promotes the formation of metallurgical bonding layers and inhibits brittle Ag2Al phase coarsening. The present study innovatively realizes the theoretical–experimental validation of the diffusion behaviors across the scales and offers a theoretical foundation for the optimization of the diffusion joining process of aluminum alloys.

Graphical abstract