Effect of Transmission Electron Microscopy Sample Preparation Methods on the Nanoscale Structure and Properties of Metallic Glasses
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Date
2015-12
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The Ohio State University
Abstract
Metallic glasses (MGs) are new metallic alloys with excellent mechanical properties. However, practical applications of MGs are still limited due to the lack of understanding on their atomic structure. Since MGs have disordered atomic structure, it is difficult to obtain the structural information that directly connects to their important properties. Recently developed transmission electron microscopy (TEM) techniques, such as fluctuation microscopy, opened new possibility in understanding the structure-property relationships in disordered materials. However, it is important to understand the effect of the TEM sample preparation methods to the structure and the quality of the samples. In the present work, we demonstrate that the structure of the MG TEM samples can change depending on the sample preparation methods. We showed that the samples prepared using mechanical polishing changed its structure, while the samples prepared using focused ion beam (FIB) showed no apparent structural change. FIB method also had other benefits, including faster preparation time and high success ratio. However, concerns still remain because FIB is known for damaging the surface of the samples, and the extent of the surface damage is difficult to quantify in disordered materials, such as MGs. Regardless, we conclude that FIB is the most efficient and reliable technique for MG TEM sample preparation. On the other hand, since mechanical polishing makes the material plastically deformed, it may be useful for studying the nanoscale deformation behavior of MGs.
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Keywords
Transmission Electron Microscopy, Fluctuation Electron Microscopy, Metallic glasses, Metallic glasses composite