The powder samples of (x = 4, 5 and 6) alloys have been measured by means of magnetization, Mössbauer effect, x-ray and neutron diffraction techniques in the temperature range 1.5 - 400 K. Both neutron and x-ray diffraction experiments showed that the positions f in all samples are occupied by iron, while the iron atoms in the samples with x = 5 and 6 locate also at j sites. A little f - j disorder exists in . The paper shows a change of the magnetic structure with an increase of iron content. The magnetic moments lie in a basal a - b plane. Iron atoms in alloy order antiferromagnetically. and alloys exhibit in general a ferromagnetic behaviour. However a detailed distribution of magnetic moments among different sites could not be determined unambiguously from the neutron data only. Nevertheless, combining information from neutron and Mössbauer experiments, one can infer that the ordering among iron atoms must be non-collinear. A magnetic ordering among uranium atoms has been found in only. Low-temperature thermal expansion varies nonlinearly with temperature and in all samples is negligible at low temperatures.