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<p>Gradient nanostructured (GNS) metals have attracted the attention of materials researchers because of their excellent mechanical properties. This work adopts molecular dynamics (MD) to conduct a series of studies on the mechanical response and crack propagation of nanocrystalline Fe, aiming to explore the intrinsic mechanism of the influence of GNS metals on the comprehensive properties of metal materials. These results indicate that the soft zone grains and hard zone grains of GNS metals have different deformation resistance abilities. Under tensile loading, compared with homogeneous nanostructured Fe (H-Fe), GNS-Fe (G-Fe) can extend the elastic deformation zone through nonuniform deformation, resulting in a higher elastic modulus and peak stress and nonuniform grain boundary (GB) migration and grain merging characteristics. For G-Fe, new cracks are prone to nucleate at the GBs near the front end of the main crack and penetrate the main crack with increasing strain, resulting in a faster crack propagation speed. However, for H-Fe, twin dislocations are prone to nucleate near the front end of the main crack, and deformation twins (DTs) and GBs jointly hinder crack propagation, resulting in a slower crack propagation speed. In addition, as the grain size gradient increases, the critical grain size of G-Fe decreases, and the strongest elastic modulus and peak stress model, such as GNS-3, are observed.</p>

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Molecular dynamics study of the mechanical behavior and crack propagation in gradient nanostructured Fe

  • 期刊论文

  • 发表日期：

    2025年6月24日

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  • Xingguo Yang,
  • Jiarui Zhang

摘要

Gradient nanostructured (GNS) metals have attracted the attention of materials researchers because of their excellent mechanical properties. This work adopts molecular dynamics (MD) to conduct a series of studies on the mechanical response and crack propagation of nanocrystalline Fe, aiming to explore the intrinsic mechanism of the influence of GNS metals on the comprehensive properties of metal materials. These results indicate that the soft zone grains and hard zone grains of GNS metals have different deformation resistance abilities. Under tensile loading, compared with homogeneous nanostructured Fe (H-Fe), GNS-Fe (G-Fe) can extend the elastic deformation zone through nonuniform deformation, resulting in a higher elastic modulus and peak stress and nonuniform grain boundary (GB) migration and grain merging characteristics. For G-Fe, new cracks are prone to nucleate at the GBs near the front end of the main crack and penetrate the main crack with increasing strain, resulting in a faster crack propagation speed. However, for H-Fe, twin dislocations are prone to nucleate near the front end of the main crack, and deformation twins (DTs) and GBs jointly hinder crack propagation, resulting in a slower crack propagation speed. In addition, as the grain size gradient increases, the critical grain size of G-Fe decreases, and the strongest elastic modulus and peak stress model, such as GNS-3, are observed.