Date of Award
Doctor of Philosophy
Physics and Astronomy
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.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Ronald L. Holtz
Holtz, Ronald L., "Low temperature thermodynamic properties of precipitation-hardening copper-beryllium alloys " (1985). Retrospective Theses and Dissertations. 7858.