<title>Fine surface modification of aluminum by laser irradiation with TiO<formula><inf><roman>2</roman></inf></formula>-Ni composite powder</title>

Surface modification experiments on aluminum were performed using CO2 laser beam irradiation on a surface on which an alloying powder had been pre-placed. Using TiO2 particles coated with Ni as a new material for laser alloying, a hard and uniformly-structured alloyed layer was achieved on the Al substrate. The effects of additive Ni on the hardness and structure of the alloyed layer were then investigated. With an increase in Ni content in the alloying powder, the hardness of the alloyed layer increased. This hardening in the alloyed layer was caused by the crystallization of intermetallic compounds. The optimum alloyed layer was obtained, when the weight ratio of TiO2 to Ni was about 1:1. The thickness of the alloyed layer was 0.6 - 0.7 mm, and the surface roughness about Rz 70 micrometers. It mainly consisted of Al+Al3Ni eutectic matrix and Al3Ti dendrites. The micro Vickers hardware of the alloyed layer was Hv200+/- 50. According to the sliding friction test, and specific wear volume was smaller than that of tempered carbon steel under high sliding speed and heavy load conditions.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.