The microstructures of Ti-AI layers (from 43-80 at %AI) produced by laser surface alloying of
titanium substrate with a powder feed technique have been investigated. The laser processing
parameters were; 1.8 kW laser power, 3 mm beam diameter, 7 mm s-a traverse speed, and
values of powder flow rates of aluminium ranging from 0.07-0.11 gs -~. The microstructures
were dendrites of 0~ 2 and interdendritic regions of 0~ 2 + y in the Ti-43 at%AI alloy; dendrites of
either 0~ 2 or 0~ 2 + y with interdendritic y in the Ti-50 at%AI alloy; dendrites of ~2 + Y with
interdendritic y in the Ti-55 at%AI alloy; single phase y in the Ti-60 at%AI alloy and TiAI 3
dendrites and AI solid solution in the interdendritic regions in the Ti-80 at%AI alloy. The
microstructures were fine and comparable to those produced by other methods of rapid
solidification processing. The microstructures of the Ti-50 and Ti-55 at%AI alloys were
in agreement with the existence of the peritectic reactions: L + [3-* ~ and L + 0~7, in the
Ti-AI system.