The Cu-Fe base alloys with liquid immiscible were prepared by gas atomization technique and conventional solidification process, the self-assemble composite microstructures in powders and bulk materials can be obtained under gravity conditions, respectively, and the minor liquid phase always forms the center of composite microstructure. It is shown that the formation of the core-type macroscopic morphology is strongly connected with the existence of a stable miscibility gap of the liquid phase in the Cu-Fe base alloys. This result can be explained by a mechanism that the minor droplets as the second phase are forced to move into the thermal center due to Marangoni motion, which is caused by the temperature dependence of interfacial energy between two liquid phases.