Agradecimentos: The authors acknowledge the financial support provided by FAPESP (Grant
Nos. 2012/08494-0 and 2013/23396-7) and CNPq (Grant Nos. 471581/2012-7 and
475480/2012-0). The authors would like to thank the Brazilian Nanotechnology
National Laboratory — LNNano for the use of X-ray diffractometer Ver menos

The dependence of tensile properties on the length scale of the dendritic morphology of Al–Cu, Al–Ag and Al–Ag–Cu alloys is experimentally investigated. These alloys were directionally solidified (DS) under a wide range of cooling rates (Ṫ), permitting extensive microstructural scales to be examined. Experimental growth laws are proposed relating the primary dendritic arm spacing, λ1 to Ṫ and tensile properties to λ1. It is shown that the most significant effect of the scale of λ1 on the tensile properties is that of the ternary alloy, which is attributed to the more homogeneous distribution of the eutectic mixture for smaller λ1 and by the combined reinforcement roles of the intermetallics present in the ternary eutectic: Al2Cu and nonequilibrium Ag3Al Ver menos