MICROSCOPIC PROCESSES ACCOMPANYING AL+-ION IMPLANTATION OF NICKEL

Nickel substrates have been implanted at room temperature with Al** plus -ions accelerated through 180 kv to fluences ranging from 1 multiplied by 10**1**5 ions/cm**2 to 4 multiplied by 10**1//8 ions/cm**2. Composition versus depth profiles were determined as were microstructures. The implanted concentration reached 75 at. % Al at the highest fluence. The variation in sputtering yield with concentration controls the increase in concentration with fluence. Phases observed include the nickel solid solution with extended aluminum solubility, an h. c. p. phase, beta prime -NiAl and an amorphous phase. Both the h. c. p. phase and the beta prime -NiAl phase form martensitically. Neither Ni//2Al//3 nor NiAl//3 are observed under implantation. Their replacements by beta prime containing 60 at. % Al and an amorphous phase, respectively, result from radiation damage.