T1 precipitate bands and particle stimulated nucleation in 2195 Al-Cu-Li alloy during hot deformation

Abstract

Dynamic precipitation and recrystallization behavior during middle-temperature and appropriate strain rates provide a chance to obtain desirable structure, which significantly improve the mechanical properties of aluminum alloys. In this paper, the microstructure evolution in the typical regions of processing map of 2195 Al-Cu-Li alloy during hot compression was observed via comparative characterization. The effects of dynamic precipitation and particle stimulated nucleation (PSN) on dynamic recrystallization have been analyzed systematically. At lower temperatures and higher strain rates, microshear band leads to a low power dissipation and provides preferential nucleation sites for T 1 precipitates. With temperature increases (<500 °C) and strain rate decreases, the T 1 precipitate bands are formed gradually due to the regular nucleation process on the microshear bands, which therefore limits the further growth of subgrains. Fine recrystallized grains along the grain boundary can also be obtained at high temperature via PSN stimulated by adequate stored energy, which was provided by large deformation near coarse secondary phases. Comprehensive continuous dynamic recrystallization (CDRX) is more prone to occur with the decrease of strain rate, leading to a higher power dissipation at 500 °C / 0.01 s −1 . • The relationship between microstructure evolution and hot processing map of 2195 Al-Cu-Li alloy have been investigated. • The formation of T 1 precipitate bands was described, and its influence on dynamic recrystallization has been discussed. • The dynamic recrystallization behaviour around grain boundaries has been discussed.