A COMPUTER SIMULATION ON LOCAL STRUCTURE AND ATOMIC-LEVEL STRESS VARIATIONS IN AMORPHOUS IRON UNDER HIGH PRESSURE

Using the static simulation method, the variations of local structure (Voronoi polyhedra statistics) and atomic-level stress in a model of amorphous iron under pressure are examined in this paper. The results show that external pressure increases the local stress and energy on each atom in the system, extends their distribution range of values and enhances the extent of fluctuation, though a homogenization of Voronoi polyhedra is promoted by the same procedure. The calculation shows that the local stresses in the structure studied divided into compressed and expansed regions, embeded each other with some percolative character. The compressed region which covers about 50 per cent atoms of the system at normal pressure and plays a role of rigid framwork of the body, will grow on increasing pressure at the expense of cosuming the expanded region. It is suggested that as the oppositely stressed regions are essentially in distinct physical conditions, they are expected to show different behaviours and give different contributions in a thermo-activated transport process. For this reason, it would be more reasonable to treat a metglas as an inhomogeneous medium on analyzing its structural relaxation mechanisms.