Rigid-Band Behavior in Aluminum-Based Alloys—Electronic Specific Heat

Abstract

Measurements of the specific heat of aluminum and its dilute alloys below 4\ifmmode^\circ\else\textdegree\fi{}K show that the electronic specific-heat coefficient $\ensuremath{\gamma}$ changes linearly with the valence electron concentration from below to above the pure-aluminum value, in contradiction to previous work. The difference is attributed to undetected precipitation of the solutes Ge or Si in the previous work. Good agreement is found between $\ensuremath{\gamma}$ values for $\mathrm{Al}\mathrm{Zn}$ alloys and the previous $\mathrm{Al}\mathrm{Mg}$ alloys. The rate of increase of $\ensuremath{\gamma}$ is three times that expected from free-electron theory. For pure Al, $\ensuremath{\gamma}=1.362$ mJ ${\mathrm{mole}}^{\ensuremath{-}1}$ \ifmmode^\circ\else\textdegree\fi{}${\mathrm{K}}^{\ensuremath{-}2}$, and the Debye temperature =431\ifmmode^\circ\else\textdegree\fi{}K.