Abstract
In a dilute alloy of aluminium, the nuclei close to the impurity experience different electric-field gradients. Using field-cycling double resonance, one can detect the pure-quadrupolar transitions of these nuclei and also the solid effect between them. In the Al-normal-metal-impurity alloys, this solid effect allows an interpretation of all the weak transitions which remained unexplained. In the Al-transition-metal-impurity alloys, a knowledge of the mechanisms of this solid effect is necessary to understand the spectra that have been obtained.