Molecular-dynamics Study on Crack Growth Behavior Relevant to Crystal Nucleation in Amorphous Metal

• Published in: Computer modeling in engineering & sciences 2005-07, Vol.9 (1), p.75-84
• Main Authors: Matsumoto, R, Nakagaki, M, Nakatani, A, Kitagawa, H
• Format: Article
• Language: English
• Subjects: Alpha iron; Computer simulation; Crack opening displacement; Crack propagation; Crack tips; Crystal structure; Crystallization; Crystals; Deformation mechanisms; Domain decomposition methods; Molecular dynamics; Nucleation; Phase transitions
• ISSN: 1526-1492; 1526-1506
• DOI: 10.3970/cmes.2005.009.075

In this paper, the internal structure-changes around the crack-tip and the pertinent crack growth behavior in an amorphous metal were studied by a molecular dynamics (MD) simulation. In order to perform a large scale calculation, the domain decomposition method was used for parallel calculation. The Finnis-Sinclair potential for$\alpha$-iron was used to describe the interatomic potential. Computed results show that nano-scaled crystalline phase grows around the crack-tip. The distribution of deformation zones and deformation mechanism are significantly altered. While grains are relatively small, they are not deformed, and the most amorphous-crystal interfaces have a large strain for phase transition. The emission of dislocations from the near crack-tip is observed after the crystal phase covered the crack-tip surfaces. Although CTOD obtained from MD analysis agrees to Dugdale's model very well during the amorphous state, the crack opening behavior changes remarkably after the crystallization.