Nanocrystalline (FexCux-1)93Zr7 (x = 0.5, 0.7) solid solution have been prepared by mechanical alloying. Structural and magnetic properties have been studied at different stages of their thermal decomposition. Differential scanning calorimetry traces show, in both alloys, two clearly differentiated exothermic processes. The first one is characterized by a heat release over a broad range of temperatures, 400-850 K, while the second is characterized by a well-defined peak at around 920 K. The structural changes that take place during these processes have been studied by X-ray diffraction. The first process can be attributed to a slow phases separation toward bcc-Fe rich and fcc-Cu rich phases. Also, from these measurements it can be concluded that during the second process the intermetallic Fe3Zr crystallizes. The evolution of saturation magnetization and coercive field with heat treatments have been studied in the temperature range from 5 to 300 K. Saturation magnetization tends to increase with thermal treatments as well as the coercive field. In addition, an anomalous behaviour in the thermal dependence of the coercive field is observed for intermediate treatment temperatures. This behaviour suggests that the thermally induced decomposition leads to a microstructure where a wide spectrum of magnetic phases with different Tc coexist.