Abstract
Laser additive manufacturing (LAM) technology was applied to prepare Ti-22Al-25Nb alloy thin-wall sample. The characteristics and evolution mechanism of solidification microstructure were investigated, and the tensile properties at horizontal and vertical directions were discussed. The results indicated that the solidification microstructure in single deposition layer evolved as: plane crystal structure, cellular crystal structure, columnar dendrite structure and equiaxed dendrite structure, from the bottom to the top of the molten pool. During the solidification process, the temperature gradient and solidification velocity decided the grain growth morphology. However, the grain of the as-deposited materials grew up to thick equaxied structure when the upper layer was forming. The tensile properties at horizontal and vertical directions were not much different, both of these exhibited high strength and low ductility.
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