Characterisation of Ni-Ti intermetallic coatings formed on Cp titanium by diffusion treatment

In order to produce a thick near equi–atomic NiTi intermetallic layer on the surface of titanium plate, layers of nickel with thicknesses of 30 µm and 60 µm were electroplated on commercial pure (Cp) titanium and subsequently were heat treated at 850°C and 900°C. The effects of heat treating temperature and the thickness of electroplated nickel on the evolution of the microstructure and mechanical properties were studied. The results confirm the formation of various intermetallic layers in the coatings that substantially affect their hardness. The optimum condition for the formation of a thick NiTi intermetallic layer on the outer surface of the titanium was diffusion treatment of the sample electrodeposited with 30 µm nickel at 900µC for 12 h. The hardness of this layer was found to be 280 HV0.15.