Notch toughness evaluations of thin film metallic glasses using FIB-based microcantilever method: A comparison study with crystalline thin films
| Autor: | Chia-Lin Li, 黎佳霖 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 106 Analysis of mechanical properties on thin films usually focus on the hardness, elastic modulus and adhesion behavior. One of the key mechanical properties on thin film is the fracture toughness, which directly affect the application. Therefore, understanding and evaluation the fracture toughness of thin film is an important issue. Metallic glass thin films (TFMGs) have many unique properties, high strength, corrosion and smooth surface. They attract many attentions in the industry and has been researched and developed for various application. Nevertheless, studies on fracture toughness of TFMGs were still insufficient in recent year. Therefore, this study measured the fracture toughness of amorphous Zr51Cu31Al13Ni5 and W33Ni32B35 TFMGs in comparison with crystalline Ti and TiN thin films as well as bulk metallic glass (BMG) using microcantilever deflection and conventional indentation methods. Deflection testing was conducted using microcantilevers fabricated by focused ion beam machining. Higher notch toughness values of 4.4, 3.84 and 5.13 MPa*m0.5 for BMG, Zr- and W-based TFMGs, respectively, than TiN (0.74 MPa*m0.5) and Ti (2.15 MPa*m0.5) films were obtained. The notch toughness of amorphous materials far exceeded those of crystalline materials. Zr-TFMG and BMG microcantilevers presented ductile fracture behavior similar to that of Ti. The results of fracture energy and vein pattern size would appear to be better than notch toughness values for the evaluation of fracture behavior. Zr-TFMG was shown to require more energy for the creation of fractures than were the other materials. Therefore, at micro-scales, metallic glasses present relatively better fracture behavior than do crystalline materials. This study presents a direct comparison of works related to the notch toughness of amorphous and crystalline materials. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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