The electronic structure of pseudobinary (T_1-xT_x')Fe₂ compounds is studied using simple models, disorder being treated using the CPA. Two models are proposed and applied to (Zr_1-xHf_x)Fe₂. The authors conclude that the 'reservoir' model is the more adequate for this series of compounds. The magnetisation and isomer shift data (measured at Fe sites) are calculated and the agreement with existing experiments is satisfactory. New experiments to confirm the predictions of the model are suggested.