The electrical resistivity of G. P. zones

Abstract

Electrical resistivities are calculated from first principles, for Al-Zn, Al-Ag, Al-Cu and Cu-Be, at various stages of age hardening. Free electron transport theory is used, in the relaxation time approximation. The calculated resistivities are fitted by phenomenological formulae, which then serve to summarize the results and to extend them to a whole range of different alloy configurations. The formulae should be useful in the interpretation of resistivity measurements, to aid the monitoring of the ageing process. It is argued that in general the resis tivity data show that the number of clusters decreases during isothermal ageing, in agreement with recent X-ray studies.