The electrical resistivity of vacuum evaporated Al-40 wt. % Zn thin fi
lms was found to decrease as thickness increased, thus exhibiting a si
ze effect. Isothermal annealing of the quenched samples started with a
n anomalous resistivity increase to maxima followed by a normal decrea
se to limiting values. In the Guinier-Preston zone temperature range a
measurable difference in resistivity was affected by the annealing te
mperature which is not the case of the bulk material. The role played
by the quenched-in vacancies, grain boundary migration, phonons and th
e state of the solute atoms were used to explain the observed resistiv
ity variations which were found to consist with the expected state of
the alloy at the different testing temperatures. The irregularities of
the position and magnitude of the observed maxima were explained in t
erms of the attenuation of the incident electron wave within the film
as a multiple scattering effect. The observed anomalies in the resisti
vity during annealing were attributed to phase transformation and atom
ic ordering.