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Electrical transport during phase transformation in metallic glasses

Citation

Schulz, Robert (1984) Electrical transport during phase transformation in metallic glasses. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-01252007-153245

Abstract

Electrical resistivity measurements have been used as a primary tool to study relaxation phenomena and high temperature structural transformations in metallic glasses. We will try to correlate, throughout this work, the resistivity behavior with structural measurements from high and low angle X-ray scattering, transmission electron microscopy, Mossbauer experiments and low temperature superconductivity measurements to get a better understanding of the scattering mechanism during the phase transformation. We will distinguish between topological relaxation and chemical relaxation and in this latter case, emphasis will be given to phase separation. Three systems will be discussed extensively. Amorphous Cu100-xZrx around the equiatomic composition, (MO0.6Ru0.4)100-xBx for boron concentrations ranging from x=14 to x=22 and (Zr1-xHfx)62Ni38 across the concentration range. We will show that upon annealing at temperature above 300°C, Cu50Zr50 phase separates into two amorphous phases of concentration close to CuZr2 and Cu10Zr7. During the phase separation an anomalous resistivity behavior, similar to the one observed during the early stage of Guinier-Preston zones formation in crystalline alloys is seen. In Mo-Ru-B alloys, the nonlinear behavior in resistivity is correlated with the presence of a peak in the small angle X-ray intensity and is explained in term of spinodal decomposition caused by the diffusion of boron in the amorphous matrix. In (Zr1-xHfx)62Ni38, an exothermic transformation which gives rise to an increase in resistivity but no resolvable Bragg peaks in the high angle X-ray pattern is investigated in detail. The applicability of the Ziman formalism to successfully explain the behavior of the resistivity in all these cases is questioned and an alternative approach, based on d-band conduction, is proposed. New ways of understanding transport phenomena during structural relaxation in metallic glasses follow from these discussions.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Physics
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Johnson, William Lewis (advisor)
  • Duwez, Pol E. (advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:23 May 1984
Record Number:CaltechETD:etd-01252007-153245
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-01252007-153245
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:340
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:09 Feb 2007
Last Modified:26 Dec 2012 02:29

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