Non Equilibrium Structures in Ion Implanted B2 Type Fe-Al and NiTi Ordered Alloys.

Two b.c.c. ordered alloys Fe-40 at % Al and Ni-Ti have been investigated by transmission electron microscopy after self ion implantation Al+ and Ni+ respectively. Partially disordered regions are observed in the Fe-40 at % Al. On the contrary, in the Ni-Ti alloy, conplete transformation to the amorphous state occured. During post implantation annealings, the precipitation of a new f.c.c. phase is observed in the Fe-40 at % Al ordered alloy, in the amorphous Ni-Ti the recrystallization occurs in a temperature range 400–550°C; the new phase has a structure either martensite type or B2 type with modulations.