Mechanical Property of Amorphous Metal with Dispersed Nanocrystalline Particle : Molecular Dynamics Study on Crystal Volume Fraction and Size Effects

摘要

In this paper, large scale molecular dynamics simulations of tensile deformation of amorphous metals with a nanocrystalline particle were performed in order to clarify the effect of particle size and crystal volume fraction on the deformation property and the strength. It became clear that the size effects of particle are very small, and the influence of the crystal volume fraction is large. The elastic modulus and the flow stress become large as the crystal volume fraction increases. After yielding of the amorphous phase, the stress of the crystal phase still increases. Thus, the flow stress of the composite increases after yielding. It 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, chances of the originating deformation are small, the inside-particle plastic deformation hardly occurs. When the crystal volume fraction is high, the particles undergo plastic deformation even with small global deformations. After yielding of the crystal particle, the flow stress decreases, because defects are introduced into the crystal. It is expected that the ideal crystal volume fraction which improve the ductility may exist. Lennard-Jones potential which is modified to enforce the continuity at the cut off distance was used. The potential parametes were defined based on Inoueu27s three basic principles.