Quasi in-situ analysis of compressive creep behaviors and microstructure evolutions in Al–Zr alloys with Sc and Er additions

Abstract

Al–Zr series alloy wires are not in a state of constant temperature and stress during service, thus the compressive stress and aging effects on the creep response in a changing state should be clarified. In this study, the quasi in-situ compressive creep behaviors and microstructure evolutions of Al–Zr alloys with Sc and Er additions have been studied. It is found that CCA curves of Al–Zr alloy were severely deformed at 120 °C for 40 h/90 MPa, for Al–Zr–Er alloy, the CCA curves sharply increased at 150 °C for 40 h/90 MPa, and that of Al–Zr-Sc alloy always kept stable at different stages. Moreover, different creep mechanisms were found in these alloys. After different CCA stages, the fibrous grains are always existing in the Al–Zr-Sc alloy, while equiaxed grains appear in the Al–Zr and Al–Zr–Er alloys, indicating the better compressive creep resistance with Sc additions. Discontinuous dynamic recrystallization (DDRX) is the dominant nucleation mechanism in the three alloys, and secondary dynamic recrystallization (SDRX) is the subordinate nucleation mechanism for the Al–Zr and Al–Zr–Er alloys. Additionally, Sc rich precipitation makes the stacking energy and lattice strain field obviously fluctuate and promotes the effective diffusion and storage of dislocations with Lomer–Cottrell locks, therefore, the compressive creep resistance of the material is improved.