Effect of Coarse Particles on Work Hardening in the Al-Mn Alloy

The effects of coarse Al₆Mn particles (~3µm) on the formation of a deformed microstructure in the Al-0.66mass%Mn binary alloy have been investigated by the tensile test and the microstructure analysis. The coarse particles have less effect on the dislocation migration in the deformation range up to ε=0.002. Due to the localization of the dislocations around the coarse particles, the maximum n-value appears in the deformation range around ε=0.02. The dislocation cells are formed in the deformation range above ε=0.10. In this stage, the localized dislocations around the particles promote annihilation of the dislocations and prevent an increase in the flow stress. For a higher deformation, the subgrains with a high angle boundary form around the coarse particles. As a consequence of these results, the Mn atoms in the coarse Al₆Mn particles have a greater effect on the work hardening than those in the matrix as solute atoms.