Precipitation phenomena, thermal stability and grain growth kinetics in an ultra-fine grained Al 2014 alloy after annealing treatment

Abstract

In the present work influence of annealing on precipitation phenomena, thermal stability and grain growth kinetics of a bulk ultrafine grained (UFG) Al 2014 alloy has been studied. As-received solution treated Al 2014 alloy is subjected to cryorolling (CR) to develop ultrafine grained microstructure and subsequently, annealing treatment in the range of 323 K (50 °C) to 673 K (400 °C) for the duration of 30 min is done to study its thermal stability. The recrystallization process of the cryorolled Al 2014 alloy starts at 373 K (100 °C) and completes at 523 K (250 °C). The UFG microstructure is retained in the CR Al 2014 alloy up to 623 K (350 °C). The high thermal stability of the UFG grained Al 2014 alloy is due to pinning action of precipitate particles of Cu₂Al and AlCuMgSi phases which are within the range of 100 nm and lying along the grain boundaries. The activation energy required for grain growth of the CR Al 2014 alloy is found to be exceptionally high as compared to other processing routes.