Large-scale molecular dynamics simulations of tensile deformation of amorphous met-als with nanocrystalline particles were performed in order to clarify the efects of particle
size and crystal volume fraction on the deformation property and the strength. It was clari-
fied that the size effects of the particle are very small, whereas the influences of the crystal
volume fraction are large. Young's modulus and the flow stress become large as the crystal
volume fraction increases. Even after the yielding of the amorphous phase, the stress of the crystal phase still continues to increase. Thus, the flow stress of the composite increases after yielding, which prevents plastic localization and improves the ductility. When the crystal volume fraction is small, the stress distribution is homogeneous in the particle including near the amorphous-crystal interface. Therefore, possibility of deformation is small, and inside- particle plastic deformation is negligible. When the crystal volume fraction is high, the parti- cle undergoes plastic deformation even with small global deformation. After the yielding of the crystal particle, the flow stress decreases because defects are introduced into the crystal. It is expected that there is an ideal crystal volume fraction that gives the maximum ductility.
A Lennard-Jones potential modified to enforce the continuity at the cut-of distance was used
as an interatomic potential. The potential parameters were defined based on Inoue's three
basic principles.