Stable second phase: The key to high-temperature creep performance of particle reinforced aluminum matrix composite

Abstract

High-temperature creep behavior of 45vol%-SiCp/2024Al was studied at 250–350 °C under 40–140 MPa. True stress exponent and activation energy were measured 8 and 227.7 kJ/mol, respectively. The feature substructure of SiCp/2024Al was the second phase Al2Cu dispersed at the interface. The evolution of microstructure and the reason for its high creep activation energy were both analyzed and discussed. θ′ phase and S′ phase underwent different evolution processes during creep. θ′ phase gradually transformed to θ phase and remain stable from the steady-state creep until creep rupture. High content of the interface facilitated the dispersion of Al2Cu. The relationship between true stress exponent and interface content as well as the key to high true stress exponent of high volume fraction particle reinforced aluminum matrix composite were also discussed. This research provided new perspectives and guidance for designing and fabricating composites with superior high-temperature creep properties.