2023, Volume 29, Issue 10
Engineering >> 2023, Volume 29, Issue 10 doi: 10.1016/j.eng.2023.01.010
The Nanoscale Density Gradient as a Structural Stabilizer for Glass Formation
a China Iron and Steel Research Institute Group, Beijing 100081, China
b Institute of Advanced Materials, North China Electric Power University, Beijing 102206, China
c Jiangsu JITRI Advanced Energy and Materials Research Institute, Changzhou 213032, China
d Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
e Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061, China
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Abstract
The rapid cooling of a metallic liquid (ML) results in short-range order (SRO) among the atomic arrangements and a disordered structure in the resulting metallic glass (MG). These phenomena cause various possible features in the microscopic structure of the MG, presenting a puzzle about the nature of the MGs' microscopic structure beyond SRO. In this study, the nanoscale density gradient (NDG) originating from a sequential arrangement of clusters with different atomic packing densities (APDs), representing the medium-range structural heterogeneity in Zr60Cu30Al10 MG, was characterized using electron tomography (ET) combined with image simulations based on structure modeling. The coarse polyhedrons with distinct facets identified in the three-dimensional images coincide with icosahedron-like clusters and represent the spatial positions of clusters with high APDs. Rearrangements of the different clusters according to descending APD order in the glass-forming process are responsible for the NDG that stabilizes both the supercooled ML and the amorphous states and acts as a hidden rule in the transition from ML to MG.
Keywords
Rapid cooling ; Amorphous solid ; Density gradient ; Electron tomography ; Atomic clusters
SupplementaryMaterials
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