Lattice modification in ion-implanted ceramics

The effect of ion implantation on alumina (Al2O3) and silicon carbide (SiC) was investigated by Rutherford backscattering (RBS), indentation hardness, fracture toughness, transmission electron microscopy (TEM), and linear scratching with a diamond stylus. The implanted (1016 to 1017 Cr X cm-2 at 280 to 300 keV, 1 to 4 X 1016 Ti X cm-2 at 150 keV, 2 X 1016 Zr X cm-2 at 150 keV) Al2O3 lattice is significantly damaged but remains crystalline; the lattice hardness increases, and the scratched surface is less sensitive to fracture. The implanted (1013 to 1016 N X cm-2 at 62 keV, 1014 to 1016 Cr X cm-2 at 280 keV) SiC lattice becomes amorphous to a depth of 250 nm, becomes less hard, and deforms without fracture when scratched. The variation in Rutherford backscattered spectra and in surface hardness with annealing are reported and interpreted in terms of lattice defects for the Al2O3 specimens