In the present article, some important trends have been shown regarding the relationship between mechanical properties, microstructure and solidification variables of Zn–Al alloys castings. Some theoretical dendritic growth models, expressing secondary spacings as function of tip growth rate or local solidification time, have been tested against experimental data obtained during unsteady-state solidification. Based on these dendritic models, on analytical expressions describing the position of solidus and liquidus isotherms in the unidirectional solidification of binary alloys and on experimental results concerning tensile testing of casting samples, expressions have been developed permitting a correlation between ultimate and yield strength, dendrite secondary spacings and solidification processing variables.