The effect of the volume fraction of nanocrystals on the brittleness of Fe-based amorphous/nanocrystalline alloys simulated by molecular dynamics

The effect of the volume fraction of body-centered cubic (BCC) crystal in Fe-based amorphous nanocrystalline alloys on room temperature brittleness was investigated via molecular dynamics simulations. Seven model samples with embedded BCC nanocrystal contents ranging from 0 to 33.4 vol.% were obtained. The indentation tests were carried out by spherical rigid indenter to investigate the microstructural evolution and the mechanical properties of those Fe-based amorphous/nanocrystalline alloys in terms of the indentation force, hardness, von Mises shear strain, atomic displacement vector as well as surface morphology. It is found virtually that the plasticity shows a gradient decrease tendency for the three types of samples with 0, less than 16, and more than 20 vol.% nanocrystal, respectively, which is caused by the free volume decreases via monitoring the Voronoi polyhedra.