“…A number of directional solidification studies have been reported in the last decades to point out the effect of microstructure upon the mechanical properties, and different approaches and equations have been used with the purpose of modeling both theoretically and experimentally the primary and secondary dendrite arm spacings as a function of alloy solute concentration (C O ), transient metal-mold heat transfer coefficient (h i ), tip growth rate (V L ), temperature gradient (G L ) ahead of the macroscopic solidification front, tip cooling rate (T R ) in the melt, type of mold and melt superheat [14][15][16][17][18][19][20][21][22][23][24][25] . Most studies have shown that for steady or unsteady growth conditions, the primary dendrite arm spacings decrease as the solidification rate or temperature gradient increases; however, there is no agreement in the literature regarding the effect of the alloy solute content on primary spacings.…”