Creep behavior and microstructure evolution during two-stage creep aging of a 2195 Al–Li alloy

Abstract

In this study, a two-stage creep aging (CA) is established by adding a new stage of low-temperature CA to the traditional single-stage CA. The results show that the two-stage CA can effectively increase the elongation (EL) of the material by about 39.2% without sacrificing strength and creep strain. In the first stage of two-stage CA, as temperature increases, EL improvement first increases and then decreases; when the temperature varies between 65 °C and 115 °C, total creep strain remains consistent. Observation of the microstructures of the specimens under different CA processes reveals that two-stage CA mainly affects the mechanical properties of the material by adjusting the properties of the GP zones inside the material in the first stage of two-stage CA, which further affects the number and size of the T1 phase in the subsequent CA process. Whether the GP zones evolve into a large number of T1 and θ′ phases in the first stage of two-stage CA can directly influence the creep strain of the entire two-stage CA process and changes in the EL of the material after CA.