Fabrication of carbide-particle-reinforced titanium aluminide-matrix composites by laser-engineered net shaping
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- Liu, W. & DuPont, J.N. Metall and Mat Trans A (2004) 35: 1133. doi:10.1007/s11661-004-1016-5
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TiAl-based titanium aluminide alloys and their composites reinforced with ceramic particles are considered to be important candidate materials for high-temperature structural applications. Laser-engineered net shaping (LENS) is a layered manufacturing process, which involves laser processing fine powders into three-dimensional components directly from a computer-aided design (CAD) model. In this work, the LENS process was employed to fabricate carbide-particle-reinforced titanium aluminide-matrix composites using Tic and gas-atomized Ti−48Al−2Cr−2Nb powders as the feedstock materials. The composites deposited by the LENS process were susceptible to solid-state cracking due to high thermal stresses. The microstructures of the laser-deposited monolithic and composite titanium aluminide materials were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS) analysis, electron-probe microanalysis (EPMA), and X-ray diffraction (XRD) techniques. Effects of the LENS processing parameters on the cracking susceptibility and microstructure were studied. Crack-free deposits were fabricated by preheating the substrate to 450 °C to 500 °C during LENS processing. The fabricated composite deposits exhibit a hardness of more than twice the value of the Ti−6Al−4V alloy.