Deformation Induced Directional Amorphization in Zr_2Ni Systems: A Remedy for the Mechanical Failure of Nano-Crystalline Alloys

摘要

We report on Molecular Dynamics results referring to the mechanical properties of crystalline, amorphous and nanocrystalline Zr_2Ni. In addition, nanocrystals of the same alloy having various sizes were also considered. With the exception of the amorphous system, we found that upon tensile deformation these systems exhibit lattice instability along the [110] direction. In addition, we found that the nanocrystals exhibit small decrease in the bulk moduli and yielding points as their sizes increased from 2 nm to 12 nm. Furthermore, it came out that in the nanocrystalline models the catastrophic failure is prevented via partial amorphization of the nanocrystals and their incorporation into the amorphous matrix, resulting in significant elongation of the plastic region. This effect results also in the increase of the triple junctions present in the system, thus altering the grain's migration angles and mobility. These findings could be used for remedying the yielding to fracture of nanostructured materials and for tailoring nanograined systems to exhibit enhanced ductility.