Nanomechanical studies of metallic glasses at ambient and elevated temperatures
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2009
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| Online Access: | http://hdl.handle.net/1721.1/46663 |
| _version_ | 1826191634643025920 |
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| author | Packard, Corinne E |
| author2 | Christopher A. Schuh. |
| author_facet | Christopher A. Schuh. Packard, Corinne E |
| author_sort | Packard, Corinne E |
| collection | MIT |
| description | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009. |
| first_indexed | 2024-09-23T08:58:59Z |
| format | Thesis |
| id | mit-1721.1/46663 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T08:58:59Z |
| publishDate | 2009 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/466632019-04-10T20:03:29Z Nanomechanical studies of metallic glasses at ambient and elevated temperatures Packard, Corinne E Christopher A. Schuh. Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Materials Science and Engineering. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009. Includes bibliographical references (p. 116-127). Bulk metallic glasses, though attractive for use in structural applications for their high strength and elastic limit, display several unacceptable features upon deformation, including quasi-brittle failure along shear bands, extremely limited tensile ductility, and propensity for fatigue under cyclic loading. Though researchers have studied metallic glasses for the last fifty years, several fundamental aspects of the mechanical deformation process in these materials have not been conclusively established. In this thesis, new instrumentation and techniques were developed to study the deformation mechanism of metallic glasses, enabling a focused, high-resolution method for probing nanomechanical behavior. A nanoindenter capable of sub-nanometer and sub-microNewton resolution was outfitted with a custom heating stage and installed in a controlled atmosphere chamber to allow for high fidelity testing in a non-oxidizing environment across a range of deformation regimes. Using this system, the process of shear band initiation near a stress concentration was investigated using a low load indentation technique, revealing that high stresses at a point directly beneath the contact are not sufficient to cause shear band release to the free surface, but instead the potential for material flow along a slip line to relieve stress must be considered. Additionally, the distribution of strengths associated with the yield event was identified and its origins were determined to be mainly structural by using a variety of specially designed loading functions to examine rate, stress, and dynamic loading dependencies. (cont.) Elevated temperature testing in the custom indentation system allowed in situ observation of the transition from discrete accommodation of strain in shear bands to homogeneous flow as well as characterization of the main features of viscous flow above the glass transition temperature. With the development of these new high-resolution testing methods, new avenues of experimental investigation have been opened, allowing insight into the fundamentals of plastic flow in metallic glasses across a spectrum of conditions. by Corinne E. Packard. Ph.D. 2009-08-26T17:15:06Z 2009-08-26T17:15:06Z 2009 2009 Thesis http://hdl.handle.net/1721.1/46663 427897729 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 129 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Materials Science and Engineering. Packard, Corinne E Nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| title | Nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| title_full | Nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| title_fullStr | Nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| title_full_unstemmed | Nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| title_short | Nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| title_sort | nanomechanical studies of metallic glasses at ambient and elevated temperatures |
| topic | Materials Science and Engineering. |
| url | http://hdl.handle.net/1721.1/46663 |
| work_keys_str_mv | AT packardcorinnee nanomechanicalstudiesofmetallicglassesatambientandelevatedtemperatures |