Formation of TiB2 whiskers in laser clad Fe–Ti–B coatings

In order to reduce the high brittleness of laser clad Fe–B coatings, the composite Fe–Ti–B coating was developed by laser cladding with a powder mixture of B4C and Fe–Ti alloy. The microstructure, hardness and cracking resistance of these coatings were investigated in this paper. The experimental work enables the following findings to be reached: (i) the needle-like TiB2 whiskers could be synthesized in situ using the laser cladding method in the composite Fe–Ti–B coating. (ii) The size, shape and volume fractions of TiB2 whiskers in the composite coating are greatly dependent upon powder compositions (contents of B, Ti elements and the ratio of B/Ti elements) and the laser energy density used. The average ratio of width/length for the synthesized TiB2 whiskers increases with increasing laser energy density and ratio of B/Ti elements in this coating. (iii) Both the hardness and cracking resistance of the Fe–B laser clad coating could be improved by the formation of TiB2 whiskers.