Effects of Mn dispersoid on hot working of Al–1Mn

The alloy Al–1Mn was deformed in torsion over the range 200–500 °C and 0.1–4 s−1 in the industrially homogenized and extruded condition. At 200 and 250 °C, the flow curves strain hardened to ε≈5 or to fracture; at higher temperatures, a steady state was reached with higher ductilities. The temperature and strain rate dependencies of the peak stress were fitted to a sinh–Arrhenius equation where Q=152 kJ mol−1. The behavior is compared with Al–0.65Fe in which Al3Fe was very effective in pinning dislocations in the range 200–300 °C with much reduced effect at 400–600 °C. Prior to deformation, limited groups of specimens were subjected to solution at 600 °C for 4 h followed by air cooling or water quenching (some specimens stretched 5%) and final aging at 350 °C for 4 h. These treatments failed to raise the strength in the range 200–300 °C.