FUNCTIONALLY GRADIENT TITANIUM ALUMINIDE COMPOSITES PRODUCED BY LASER CLADDING

The laser surface cladding of Ti-Al/TiB2 composites was investigated as a means of producing a functionally gradient material on a commercially pure Ti substrate. Single and double layers were produced. The processing parameters were: 1.7 kW laser power, 3 mm beam diameter, 3-22 mm s-1 traverse speeds, 2.2-6.2 g min-1 powder flow rates. The results showed that functionally gradient Ti-Al/TiB2 systems approximately 2 mm thick, with a progressive increase in the Al content from 0 to 35 wt% Al (50 at % Al) could be produced by vertically overlapping two clad layers using powder mixtures of selected compositions. Microstructural and compositional characterization were performed on single-layer and two-layer clads. Preliminary wear testing carried out on a laser surface Ti-Al/TiB2 single-clad layer and on commercial-purity titanium demonstrated the beneficial effect of laser cladding on the wear resistance.