Formation of Intermetallic Coatings by Mechanical Alloying Tehhnique

The mechanical alloying (MA) technique was applied to produce intermetallic Ti-Al and/or Ni-Al coatings on the titanium or nickel surface. Milling was conducted in steel vial with steel balls using elemental powders (Ti and Al or Ni and Al ) and titanium or nickel substrate at room temperature. During MA processing, the sample surface was impacted by a large number of flying balls along with particles of powder. The repeated ball collisions with the sample resulted in deposition of powder on the surface. The dependence of thickness of coatings from an amount of powders and time of MA were investigated using Ni-Al system for different amplitude of frequency. The coatings appear to be homogeneous, with a high density and free of porosity, and have excellent adherence to the substrate. During annealing, on the surface of the Ti samples coated with Al+Ti layer, aluminide overlayers were formed as the result of reactions between Ti and Al. The coatings were characterized using X-ray diffraction and scanning electron microscopy.