The Effect of Y-Ion Implantation on the Oxidation of β-NiAl

摘要

The influence of Y-ion implantation on the oxidation of β-NiAl single crystals has been investigated using SEM, TEM, and STEM. Y ions having an energy of 70 ke V were implanted with a concentration of 5 x 10~(16) ions/cm~2. The oxidation experiments were performed in air at 1223 K. Y-ion implantation resulted in a 45-nm disordered layer. Oxidation of Y-implanted β-NiAl leads to the formation of a fine-grain layer, consisting of γ-Al_2O_3 containing Y and a θ-Al_2O_3 layer. After further oxidation the metastable Al_2O_3 transformed into α-Al_2O_3, which started at the metal-oxide interface. Y-Al-garnet (YAG) particles were observed and Y segregation to α-Al_2O_3 grain boundaries has been detected.