Rapidly solidified microstructure of Ti60 alloy produced by laser rapid forming process

Bar and plate-like samples of high-temperature titanium alloy Ti60 were produced by laser melting deposition manufacturing process. Rapidly solidified microstructure and precipitation behavior of rare earth-rich phases in the laser melting deposited Ti60 alloy were studied. The microstructure of the Ti60 bar sample is composed of directionally solidified " splayed " columnar grains with bar specimen's axes as its symmetry axes. The inner of the columnar grains has fine and uniform directional rapidly solidified full cellular structure, with extremely fine rare earth-rich phases distributed along the sub-grain boundaries. The laser multiple-track-overlap layer-by-layer melting deposited Ti60 plate-like specimen has uniform and ultra-fine directional rapidly solidified full cellular structure formed in " zig-zag " alternate growth, with a cell spacing as low as 5~9μm. The rare earth-rich phases in the plate-like specimen are much finer and denser than that of bar-like sample.