High current Ni- and Fe-ion implantation into an Al surface to modify the mechanical properties

The surface modification of Al was studied by high current Ni- and Fe-ion implantation using a metal vapor vacuum are ion source. The strengthening intermetallic aluminides were formed after Ni- and Fe-ion implantation to doses in the order of 10(17)-10(18) ions cm(-2). The depth profiles of the hardening phases were found to depend on the ion current density as well as the dose. In the case of Ni-implantation, when implanting with a current density of 89 mu A cm(-2) to a dose of 6 x 10(17) ions cm(-2), the Al3Ni phase in the near surface was enriched up to 85 vol.% and extended into a depth of about 4000 Angstrom. In the case of Fe-ion implantation, a dual implantation resulted in an almost unique Al13Fe4 compound standing in the near surface layer of 1000 Angstrom in thickness and spreading to 4500 Angstrom in depth. Accordingly, the microhardness of the implanted Al films was measured and found to be considerably increased. The mechanisms responsible for the formation of intermetallic aluminides and surface hardening are also discussed. (C) 1998 Elsevier Science S.A. All rights reserved.