Laser alloy experiments using TiO2 particles coated with Ni by electroless plating were conducted to form a hard, structurally uniform alloyed layer on an Al substrate. The alloyed layer formed using this TiO2-Ni composite powder had a smoother surface and a more uniform structure than layers formed using TiO2 or Ni powder independently because composite powder featured high absorption for a CO2 laser beam and good reaction on melted Al. Increasing Ni content in the alloy powder, increased alloyed layer hardness due to the crystallization of intermetallic compounds. The optimum alloyed layer was obtained when the weight ratio of TiO2 to Ni was about 1:1. The alloyed layer was 0.6-0.7mm thick and surface roughness about Rz 70 microns. The micro-Vickers hardness of the alloy was Hv 200±50. TiO2-Ni composite powder is thus useful in laser alloy.
