The effect of aluminium addition on the magnetic moments of the constituent atoms of binary BCC Fe-Co, Fe-Cr and FCC Ni-Fe alloys was investigated by comparing the results of Mossbauer and average magnetization measurements. It was found that the Al neighbours do not perturb the moment of Fe atoms in the Fe-Co and Ni-Fe alloys whereas there is a decrease in the Co and Ni moments. This different behaviour of Fe, Co and Ni towards the Al diluent is explained in terms of a simple local model. The simple model does not, however, explain the effects produced by Al in the BCC Fe-Cr alloys.