The Al-6wt%Cu alloy was directionally solidified and dendritic microstructure, solidification thermal variables, i.e., tip growth rate (VL), cooling rate (TR) and temperature gradient ahead of liquidus isotherm (GL) were characterized and correlated with tertiary dendritic spacings ((λ3) determined experimentally. For this purpose, a horizontal solidification experimental apparatus was developed and specimens were solidified under unsteady state heat flow conditions. It was observed that power laws -1.1 and -0.55 characterize the tertiary spacing variations with tip growth rate (VL) and cooling rate (TR), respectively. Comparisons with other studies published in the literature for Al-Cu alloys solidified in upward and downward vertical directional conditions were performed.
horizontal directional solidification; tertiary dendritic spacing; Al-Cu alloys
