Mechanism of Ultrafine Grain Formation during Equal Channel Angular Extrusion in an Aluminum Alloy at Intermediate Temperature

摘要

The mechanism of grain formation during equal channel angular extrusion (ECAE) in a 2219 aluminum alloy has been studied at T=250°C. It was shown that continuous dynamic recrystallization (CDRX) occurred during intense plastic straining and resulted in formation of submicrometer scale grains. An important feature of CDRX is formation of a low energy dislocation structure (LEDS) after first passage, which provides high stability to the evolving subgrain structure. Such a structure transforms into a recrystallized granular structure at a high rate with increasing strain. The mechanism of CDRX is discussed.