Microstructure formation of metallic nanoglasses: Insights from molecular dynamics simulations

We investigate the microstructure formation of Pd80Si20 and Cu64Zr36 nanoglasses by molecular dynamics simulations of the consolidation process of nanometer-sized metallic glassy spheres. Our results reveal that during cold compaction most of the glassy spheres deform by homogeneous plastic flow and in some glassy spheres strain localization occurs in a shear band which traverses the whole glassy sphere. Moreover, the porosity is closed if hydrostatic pressures exceed 4 GPa. The resulting nanoglasses are composed of glassy regions connected by glass-glass interfaces. The results reveal that the width of these interfaces is significantly larger than estimated in previous atomistic models based on planar interfaces. Moreover, structural changes occur not only in the interfaces but also in the glassy regions. In addition, thermodynamics analysis show that surface segregation is favorable in the primary glassy spheres but not always in the nanoglass. The present findings shed light on the process of the microstructure formation of metallic nanoglasses and can serve to interpret the experimental results. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.