Both Cu and Fe metals, with face-centered cubic (fcc) crystal structures, are nonmagnetic. However, the substitution of Cu atoms by Fe in the fcc-Cu lattice leads to the formation of a random solid solution and the appearance of ferromagnetic order, with a value of the magnetic moment per Fe atom in a fcc environment even above 2mu(B). This striking behavior is closely related to magnetovolume effects (Invar), which we have detected by means of lattice thermal expansion and magnetization measurements in FeCu alloys.