The formation mechanism of mechanically alloyed Fe–20at% Al powder
Résumé
The formation mechanism of the mechanically alloyed Fe–20 at% Al, from elemental Fe and Al powders, has been investigated. The experimental results indicate the formation of a nanocrystalline bcc α-Fe(Al) solid solution with a lattice parameter close to aα−Fe(Al)=0.2890 nm, where each Fe atom is surrounded by (6Fe+2Al) in the first coordination sphere. The reaction mechanism of MA process seems to be controlled by a diffusion phenomenon. Aluminum particles undergo an important refinement to the nanometer scale and then they stick on Fe particles of large sizes. A large number of clear Al/Fe interface areas were generated. The short diffusion path and the presence of high concentration of defects accelerated the solid state reaction.