[en] We present the results of low-temperature dc magnetization measurements performed on Y_0.8U_0.2Pd₃ and UCu₄Ni samples for magnetic fields up to 90 kOe. Both systems have been reported to show electrical, thermal and magnetic properties suggestive of the development of 'non-Fermi liquid' (NFL) behavior at low temperatures. The origin of this behavior has been a matter of controversy for more than one decade. In this work, we will discuss our results in terms of the current models proposed to explain the breakdown of Fermi-liquid theory observed in this type of materials. Special attention will be paid to the Griffiths phase and Kondo disorder models, which emphasize the role of structural and compositional disorder