The effect of Cr- and Y-implantation on the isothermal and cyclic oxidation
behaviour in air of a boron doped Ni3Al alloy at 585 and 900 degrees C for
up to 200 h is discussed. Yttrium implantation proved to be detrimental, c
ausing slightly higher oxidation rates at both temperatures, while the scal
e formed at 900 degrees C on Y implanted Ni3Al was prone to spallation. Aft
er 200 h at 585 degrees C (isothermal or cyclic oxidation) the scale consis
ted of an outer NiO layer, an intermediate Ni and al rich oxide zone, and a
n inner thin alumina layer. A similar scale pattern was observed for the no
n-implanted material, however, the oxide scale formed on the non-implanted
material did not show any significant susceptibility to scale cracking and
spallation. Chromium implantation on the other hand was beneficial in that
it decreased the oxidation rates at both temperatures owing to the formatio
n of a continuously healing alumina layer, induced by the presence of chrom
ium. No spallation of the oxide scale occurred, even after 200 cycles at 90
0 degrees C. MST/3882.