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Investigation of Capacitive Discharge Heating of Metallic Glasses

Citation

Kaltenboeck, Georg (2016) Investigation of Capacitive Discharge Heating of Metallic Glasses. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9251G5Z. http://resolver.caltech.edu/CaltechTHESIS:05122016-150703449

Abstract

In recent years, the discovery of bulk metallic glasses with exceptional properties has generated much interest. One of their most intriguing features is their capacity for viscous flow above the glass transition temperature. This characteristic allows metallic glasses to be formed like plastics at modest temperatures. However, crystallization of supercooled metallic liquids in the best bulk metallic glass-formers is much more rapid than in most polymers and silicate glass-forming liquids. The short times to crystallization impairs experimentation on and processing of supercooled glass-forming metallic liquids. A technique to rapidly and uniformly heat metallic glasses at rates of 105 to 106 kelvin per second is presented. A capacitive discharge is used to ohmically heat metallic glasses to temperatures in the super cooled liquid region in millisecond time-scales. By heating samples rapidly, the most time-consuming step in experiments on supercooled metallic liquids is reduced orders of magnitude in length. This allows for experimentation on and processing of metallic liquids in temperature ranges that were previously inaccessible because of crystallization.

A variety of forming techniques, including injection molding and forging, were coupled with capacitive discharge heating to produce near net-shaped metallic glass parts. In addition, a new forming technique, which combines a magnetic field with the heating current to produce a forming force, was developed. Viscosities were measured in previously inaccessible temperature ranges using parallel plate rheometry combined with capacitive discharge heating. Lastly, a rapid pulse calorimeter was developed with this technique to investigate the thermophysical behavior of metallic glasses at these rapid heating rates.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Metallic Glass, Amorphous, Metals, Thermoplastic, Supercooled Liquid
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Materials Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Johnson, William Lewis
Thesis Committee:
  • Johnson, William Lewis (chair)
  • Fultz, Brent T.
  • Faber, Katherine T.
  • Goddard, William A., III
  • Demetriou, Marios D.
Defense Date:11 December 2015
Non-Caltech Author Email:georg.kaltenboeck (AT) gmail.com
Funders:
Funding AgencyGrant Number
II-VI FoundationUNSPECIFIED
Record Number:CaltechTHESIS:05122016-150703449
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05122016-150703449
DOI:10.7907/Z9251G5Z
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1126/science.1201362DOIArticle adapted for ch. 1
http://dx.doi.org/10.1038/srep06441DOIArticle adapted for ch. 2
http://dx.doi.org/10.1038/ncomms10576DOIArticle adapted for ch. 3
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9718
Collection:CaltechTHESIS
Deposited By: Georg Kaltenboeck
Deposited On:19 May 2016 21:16
Last Modified:28 Apr 2017 18:12

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