Observations of quenched-in resistivity in alpha brasses showed an apparent decrease in the activation energy of vacancy formation with increasing zinc content, from a value of 0.85eV for analytically pure copper to 0.30eV for Cu-35%Zn alloy. This effect was attributed to the enhanced formation of zinc-vacancy pairs.

Dependence of the Activation Energy of Vacancy Formation on the Zinc Content in Alpha Brasses. R.Kamel, T.H.Youssef: Czechoslovak Journal of Physics, 1968, 18[6], 738-42