Hardening and softening in milled nanostructured FeAl on annealing

Changes of hardness occurring in milled FeAl intermetallics on annealing are examined and compared with the behaviour of conventional disordered Fe-base materials. A hardness peak is seen after annealing to about 500–600 °C which is explained by the precipitation and growth of fine oxide particles. There is no evidence to support any role of the state of order nor the presence of partial dislocations in affecting the hardness.