Excess free volume and structural properties of inert gas condensation synthesized nanoparticles based CuZr nanoglasses

Abstract

Nanoglass (NG) as a new structure-tunable material has been investigated using both experiments and computational modeling. Experimentally, inert gas condensation (IGC) is commonly employed to prepare metallic glass (MG) nanoparticles that are consolidated using cold compression to generate an NG. In computational modeling, various methods have been used to generate NGs. However, due to the high computational cost involved, heretofore modeling investigations have not followed the experimental synthesis route. In this work, we use molecular dynamics simulations to generate an NG model by consolidating IGC-prepared Cu64Zr36 nanoparticles following a workflow similar to that of experiments. The resulting structure is compared with those of NGs produced following two alternative procedures previously used: direct generation employing Voronoi tessellation and consolidation of spherical nanoparticles carved from an MG sample. We focus on the characterization of the excess free volume and the Voronoi polyhedral statistics in order to identify and quantify contrasting features of the glass-glass interfaces in the three NG samples prepared using distinct methods. Results indicate that glass-glass interfaces in IGC-based NGs are thicker and display higher structural contrast with their parent MG structure. Nanoparticle-based methods display excess free volume exceeding 4%, in agreement with experiments. IGC-prepared nanoparticles, which display Cu segregation to their surfaces, generate the highest glass-glass interface excess free volume levels and the largest relative interface volume with excess free volume higher than 3%. Voronoi polyhedral analysis indicates a sharp drop in the full icosahedral motif fraction in the glass-glass interfaces in nanoparticle-based NG as compared to their parent MG.

Evidence for Glass–glass Interfaces in a Columnar Cu–Zr Nanoglass

“…[ 26 ] Thus, the observed changes are well within the expected range. Simulations on CuZr nanoglasses yielded an increase of the excess volume by 4% [ 27 ] while simulations on CuTi nanoglasses suggested an increase by about 10%. [ 1 ]…”

“…[26] Thus, the observed changes are well within the expected range. Simulations on CuZr nanoglasses yielded an increase of the excess volume by 4% [27] while simulations on CuTi nanoglasses suggested an increase by about 10%. [1] Naturally, such a large increase of the excess volume needs to be accompanied by significant structural modifications.…”

Study on liquid-like SiGe cluster growth during co-condensation from supersaturated vapor mixtures by molecular dynamics simulation

“…Instead of the isothermal MD method, 18,[24][25][26][27][28] we applied the simulations with cooling from high temperatures to mimic the cluster formation during the CVD deposition. The simulation results described the clusters during the growth process in detail and clearly demonstrated the history of cluster formation.…”