Formation of the phases Ti3Al and TiAl by high-dose implantation of aluminium into titanium

Surface modification of titanium is of interest considering the necessary i mprovement of mechanical properties of this material for applications as e. g. artificial joints. This work is devoted to the formation of a layer with a high content of the titanium aluminides Ti3Al and TiAl below the surface by high-dose aluminium implantation. If the maximum aluminium concentratio n exceeds 20 at.%, precipitation of Ti3Al is detected by XRD already in the as-implanted state. For maximum aluminium concentrations between 50 and 55 at.%, the phase TiAl is found beside Ti3Al after annealing at 700 degrees C. For a double implantation resulting in an aluminium concentration of abo ut 60 at.% in the depth range between 100 and 200 nm, a disordered fee TiAl phase is observed after implantation as precursor for the ordered tetragon al TiAl formed by subsequent annealing at 600 degrees C. (C) 2000 Elsevier Science B.V. All rights reserved.