Abstract
High mechanical strength is one of the superior properties of metallic glasses which render them promising as a structural material. However, understanding the process of mechanical deformation in strongly disordered matter, such as metallic glass, is exceedingly difficult because even an effort to describe the structure qualitatively is hampered by the absence of crystalline periodicity. In spite of such challenges, we demonstrate that high-energy synchrotron X-ray diffraction measurement under stress, using a two-dimensional detector coupled with the anisotropic pair-density function (PDF) analysis, has greatly facilitated the effort of unraveling complex atomic rearrangements involved in the elastic, anelastic, and plastic deformation of metallic glasses. Even though PDF only provides information on the correlation between two atoms and not on many-body correlations, which are often necessary in elucidating various properties, by using stress as means of exciting the system we can garner rich information on the nature of the atomic structure and local atomic rearrangements during deformation in glasses.
Highlights
Glass generally is a symbol of something extremely fragile
Most physical properties depend on more collective atomic correlations, which diffraction measurements cannot directly assess
We show typical results obtained for the sample treated with thermomechanical creep to demonstrate how the anisotropic pair-density function (PDF) can be determined
Summary
Glass generally is a symbol of something extremely fragile. conventional glasses, mostly oxide glasses, shatter helplessly upon impact. A relatively new family member of glasses, metallic glass, is stronger and tougher than oxide glasses, and even compares favorably to most of crystalline metallic materials in their mechanical properties. For this reason they are promising as structural materials [1], and are beginning to be used in watches and mobile phones. Defects cannot be uniquely defined because of the extensive disorder in their structures. Phenomenologically structural defects, such as the shear-transformation-zones (STZs), have been postulated and have facilitated elucidation of mechanical properties [2,3].
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