Solidification is an important phase transformation in materials science and engineering. The imposition of a wide range of operational conditions in foundry and castings process generates, as a direct consequence, a diversity of solidification structures. A low carbon steel mold was used to promote a unidirectional heat flow during solidification and to obtain the arrangement of the microstructure. The aim of the present work is to investigate the influence of microstructure on mechanical properties of nonferrous metals, specifically aluminum alloys and copper alloys. Experimental results include phases, primary and secondary dendrite arm spacings, hardness, ultimate tensile strength and yield strength as a function of solidification conditions imposed by the metal/mold system. Finer microstructures tend to improve the mechanical resistance of aluminum alloys and copper alloys.