Functionally gradient titanium-aluminide composites produced by laser cladding

Abstract

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 mms⁻¹ traverse speeds, 2.2–6.2 g min⁻¹ powder flow rates. The results showed that functionally gradient Ti-Al/TiB₂ systems ∼ 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.