Degree Type

Dissertation

Date of Award

1985

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

Abstract

An unusual enhancement has been found in the ratios of the specific heats of copper-beryllium solid-solutions to the specific heat of pure copper. The magnitude of this effect represents an apparent 5% increase of the alloy specific heat, peaking near 20 K. Specific heat measurements from 1 K to 60 K on a Cu-1.92wt.% Be alloy and on the commercial alloy Berylco-25 show that the size of the enhancement is reduced by precipitation-hardening;Measurements of the linear thermal expansivity from 4 K to 300 K of CUBE-250, an alloy similar to Berylco-25, also show an enhance- ment effect. No unusual behavior was found in the electrical resis- tivity of Berylco-25 between 1 K and 80 K;It is suggested that the apparent enhancement of the Cu-Be specific heat is due to slight shifts of the phonon frequencies in the alloy with respect to pure copper. The Debye temperature of the Cu-Be solid-solution is nearly the same as that of copper (345 K). The electronic density of states at the Fermi level is slightly higher for the alloy;Precipitation-hardening is associated with formation of particles of the CuBe intermetallic phase within the solid-solution matrix. The apparent specific heat enhancement is reduced for the hardened condition due to depletion of the Be concentration in the matrix. With precipitation-hardening, the Debye temperature of the alloy;increases, and the electronic specific heat contribution approaches that of copper; *DOE Report IS-T-1108. This work was perfomed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.

DOI

https://doi.org/10.31274/rtd-180813-6168

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Ronald L. Holtz

Language

en

Proquest ID

AAI8514410

File Format

application/pdf

File Size

160 pages

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