EFFECTS OF ALLOYING ELEMENTS AND SOLIDIFICATION CONDITIONS ON SECONDARY DENDRITE ARM SPACING IN ALUMINUM ALLOYS

摘要

Published and unpublished experimentally determined values of secondary dendrite cell size and arm spacing in aluminum alloys as a function of solidification conditions and alloy composition have been reviewed and collated. Functional empirical models for predicting the effects of alloying elements, solidification rate, and local solidification time on secondary dendrite arm spacing in binary and multicomponent aluminum alloys have been developed. Results of the study indicate that secondary dendrite arm spacing (or cell size) in aluminum alloys generally decrease with increase in solidification rate and by addition of Ti, Cu, Fe and Si. Conversely, secondary dendrite arm spacing (or cell size) in cast aluminum products increases with increase in local solidification time and by addition of Zn. Mg, the most widely used alloying element in the aluminum industry, does not have any statistically significant effect on dendrite coarsening in commercial aluminum alloys.