Atomistic study of crack growth behavior in crystalline Mg/amorphous Mg-Al nanocomposites

The effects of crystalline boundary (CB) spacing and crystal orientation on the crack propagation behavior in crystalline/amorphous (C/A) Mg/Mg-Al nanocomposites under tensile loading are investigated using molecular dynamics simulation method. Three samples with different crystal orientations of initial crack are considered. The results show that although both samples with cracks exhibit plasticity, the deformation mechanisms are drastically different. For samples A and C with larger CB spacing, the deformation twinning and the nucleation and growth of new grain dominate the crack plastic deformation. For samples A and B with smaller CB spacing, the dislocation and interfacial slip are important plastic deformation mode at crack top. However, the crack plastic deformation of sample C with small CB spacing is mainly induced by the nucleation and growth of new grain in neighbor crystalline phase sections. The above mentioned crack deformation behaviors of C/A Mg/Mg-Al nanocomposites are also disclosed and analyzed in present work. The results here provide a strategy for the design of high-performance hexagonal-close-packed metal and alloy materials.