THERMODYNAMICS-BASED COMPUTATIONAL APPROACH TO Al-Cu ALLOYS: GRAIN REFINEMENT

To describe the solute effect on grain refinement, the growth restriction factor (Q) in multicomponent multiphase Al alloys has been often evaluated using a simple summation of the Q values of the individual constituents taken from the binary alloy diagram. Such kind of evaluation can lead to mistakes, or completely fail when an intermetallic phase, even in a trace amount, solidifies prior to the primary alpha-Al. A more accurate method to evaluate growth restriction factor (Q(true)) from thermodynamic descriptions is to calculate the initial slope in the development of constitutional supercooling (Delta T) with the phase fraction of the growing solid phase (f(x) ). In this contribution, ThermoCalc software (with TTA15 database) was used to evaluate the Q(true) in a series of Al-Cu based alloys with Ti, Zr and Sc additions. This investigation demonstrates that thermodynamic-based alloy design can provide a significant tool to develop novel Al alloys.