Thermodynamics-Based Computational Approach to Al-Cu Alloys: Grain Refinement

Abstract

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 α-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 (ΔT) with the phase fraction of the growing solid phase (f _s ). 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.