Al-Mm-Ni-(Fe,Co) alloys of six slightly different compositions were melt spun to amorphous ribbons. DSC studies of the ribbons show that the first crystallization stage, responsible for the precipitation of fcc-Al, is well separated from the others. Mixed structures containing nanosized fcc-Al crystals, embedded in amorphous matrix were obtained by isothermal annealing of the initially amorphous ribbons for different times and thus, different crystalline fractions the fcc-Al crystals were obtained. The microhardness of the alloys increases with the increase of annealing time, reaching a "plateau" after about 20 min of annealing. Replacing Fe by Co does not significantly influence the microhardness of these alloys. The slight changes of chemical composition don’t seem to have a clear effect on microhardness.