Effects of solidification range on macro- and microstructure of pure aluminium and binary Al–Cu alloys obtained under conditions of constant melt flow are studied experimentally. The solidification range of binary alloys was varied by changing the concentration of the alloying element. An electromagnetic pump with a specially designed melt-guiding system is used to organize controlled unidirectional melt flow along the solidification front. Temperature and melt flow velocity are controlled during the experiment. It is observed that the extent of solidification range changes the macro– and microstructure, affects width and deflection angle of columnar grains, and alters the dendrite arm spacing in the presence of melt flow. The melt flow itself is found to change the macro- and microstructure, e.g. the increase of melt flow velocity clearly decreases the dendrite arm spacing.