Stability of Al0.75Ni0.25 amorphous zones induced by Ni ion implantation into pure aluminium

Implantation of Ni ions into pure aluminium shows the formation of amorphou s zones (AZ). Measurements by energy dispersive spectrometry attribute to t he amorphous zones at Ni concentration of 25 at.%. These amorphous regions are relatively stable under heating and persist after post-implantation tre atment. To understand microscopically this stability, molecular dynamic sim ulations (MD) are done. Using embedded atom method potentials, an amorphous Al3Ni is first obtained. The melting temperature determined for this sampl e from the calculations is in good agreement with the experimental data. A spherical amorphous zone is then introduced into a crystalline aluminium ma trix. After relaxation to obtain the equilibrium at interface, the system i s heated for hundreds of picosecond at various temperatures. The AZ remains after this treatment. One cascade of 5 keV is then simulated inside an AZ. A complete phase transition is not observed, but a partial recrystallizati on is present. (C) 1998 Elsevier Science B.V. All rights reserved.