Structure of TiB 2 produced by dynamic ion mixing

Abstract

The new technique of dynamic ion mixing is based on the use of a high energy ion beam to homogenize at the atomic scale and to improve the adherence of a growing film on any substrate. TiB 2 films of stoichiometric composition are produced either by co-evaporation or by dynamic ion mixing using 100 keV Ar + ions. The characterization of the films is performed by transmission electron microscopy (TEM) . The results indicate that the ion mixing of the growing film has a crucial importance with regard to the resulting microstructural state. Amorphous TiB 2 films are produced by conventional co-evaporation although crystalline TiB 2 films of hexagonal structure are produced by dynamic ion mixing. The TiB 2 amorphous phase appears to be very stable since crystallization starts only at about 1170 K and complete transformation into the hexagonal crystalline structure is obtained at 1280 K. Relatively thick TiB 2 coatings have been prepared with e = 1 μm and studied by TEM on cross-sectional preparations. The microhardness of crystalline TiB 2 films is about 2800 kgf mm −2 and is in good agreement with the value reported for bulk TiB 2.