Evolution of Microstructure and Mechanical Properties of an Al-3Mg Alloy during Equal Channel Angular Pressing and Subsequent Annealing

摘要

ECAP (Equal Channel Angular Pressing) is a materials processing method that allows very high strains to be imposed, leading to extreme work hardening and microstructural refinement. The microstructure of an Al-Mg alloy is examined after processing by ECAP as well as its evolution during subsequent heat treatments for precipitation, recrystallization, or grain coarsening. Fine microstructures are produced by deformation which coarsen steadily on annealing. The grain boundaries present after deformation as well as after annealing are generally of very low angle misorientations, and different textures are obtained than after heavy deformation by conventional deformation processing. Much of the strengthening observed can be explained by Hall-Petch strengthening, with additional strengthening due to the high dislocation density of the deformed state.