Propagation of mode I crack along bi-metal (001) interfaces of Fe/W, Fe/Ni, Fe/Co and Ti/Mg is simulated by molecular dynamics and discussed with the eigenvalue/vector of the atomic elastic stiffness, $B_{ij}^a=\mathrm{\Delta }{\sigma }_i^a/\mathrm{\Delta }{\epsilon }_j$, and surface energy. The crack does not propagate at the interface but in the adjacent phase of smaller surface energy, except in Fe/Ni. The 1st eigenvalue η^a(1), or the solution of $B_{ij}^a\mathrm{\Delta }{\epsilon }_j={\eta }^a\mathrm{\Delta }{\epsilon }_i$ of each atom, clarifies the difference of ‘soft/hard’ of both phases at the onset of crack propagation. In the case of Fe/Ni, the η^a(1) of Ni atoms remarkably decreases in the Fe/Ni bi-metal structure, even though Ni has higher η^a(1) than Fe at no-load perfect lattices. Thus the rupture occurs in the Ni side even though the Ni has slightly higher (001) surface energy than Fe. Deformation modes at the crack propagation are also visualized by the eigenvector of η^a(1) < 0 unstable atoms.

This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.

通过分子动力学模拟了I型裂纹沿Fe / W，Fe / Ni，Fe / Co和Ti / Mg的双金属（001）界面的传播，并利用原子弹性刚度的特征值/矢量进行了讨论， ${乙}_{\mathrm{一世}Ĵ}^{\mathrm{一种}}=\mathrm{\Delta }{\sigma }_{\mathrm{一世}}^{\mathrm{一种}}/\mathrm{\Delta }{\epsilon }_{Ĵ}$和表面能。除Fe / Ni外，裂纹不在界面处传播，而是在表面能较小的相邻相处传播。所述第一特征值η^一（1） ，或溶液${乙}_{\mathrm{一世}Ĵ}^{\mathrm{一种}}\mathrm{\Delta }{\epsilon }_{Ĵ}={\eta }^{\mathrm{一种}}\mathrm{\Delta }{\epsilon }_{\mathrm{一世}}$每个原子的原子序数，阐明了裂纹扩展开始时两相“软/硬”的差异。在铁/镍，所述的情况下，η^一（1） Ni原子的在铁/镍的双金属结构显着降低，即使Ni具有更高η^一（1）比Fe空载完美晶格。因此，即使Ni具有比Fe稍高的（001）表面能，也会在Ni侧发生破裂。在裂纹扩展变形模式也由的特征向量可视η^一（1）  <0不稳定原子。

本文是主题主题“固体材料的断裂动力学：从粒子到地球”的一部分。