Accelerated discovery of potential heat-resistant Al8Cu4X phases via high-throughput first-principles calculations

The Al8Cu4X phase has emerged as a promising heat-resistant strengthening candidate for Al-Cu alloys, mitigating the instability of Ω/θ′ precipitates at elevated temperatures. In this work, we employ high-throughput first-principles calculations to systematically investigate 57 Al8Cu4X compounds, focusing on their thermodynamic stability and phase trans-formation behavior. Density functional theory calculations reveal negative formation energies for 53 compounds, and those containing rare earth elements, Ca, Sr, and Y are identified as favorable candidates for forming microscale phases at high temperatures. Phase transformation energies exhibit a pronounced periodic trend, with 33 compounds showing negative values, supporting the feasibility of forming nanoscale strengthening precipitates via high-temperature phase transformation. Symbolic regression analysis further identifies atomic volume as the primary descriptor governing the phase transformation energies, while bond order analysis demonstrates that the enhanced stability originates from a strengthened Al-Al bonding network and newly introduced Al-X bonds within the Al8Cu4X structures. Overall, this work provides a theoretical foundation for the future design and application of heat-resistant Al8Cu4X phases in aluminum alloys.