NMR Investigation of Atomic Structure and Dynamics of Bulk Metallic Glasses
Abstract
Metallic glasses are amorphous solids consisting of densely packed atoms. Unlike in crystalline solids where point defects and topological defects can be defined unambiguously such as vacancies and dislocations, the structural complexity of metallic glasses makes it rather difficult, for instance, to even describe changes of atomic structures upon mechanical deformation, let alone measure them quantitatively. This makes it extremely challenging to identify experimentally atomic structural changes with certain mechanical properties such as anelastic and plastic deformations, a critical step for optimizing mechanical properties of metallic glasses for applications. We demonstrated that, via Al-27 nuclear magnetic resonance (NMR) measurements, that atomic level structures characterized by electric-field-gradient tensors and the electronic properties characterized by the Knight shift-both are sensitive parameters for understanding the mechanical properties of metallic glasses such as the toughness and anelastic deformation. For instance, it was found that the local site symmetry at Al sites measured by NMR changes sensitively under anelastic deformation and there is a strong correlation between hardness and toughness with local electronic properties measured by NMR. These findings established a new approach to understand mechanical properties of glassy metals at atomic scales and could lead to optimized metallic glasses with improved mechanical properties.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 17, 2013
- Accession Number
- ADA592532
Entities
People
- Yue Wu
Organizations
- University of North Carolina at Chapel Hill