The microstructure evolution of TC4-(TiB + TiC)/TC4 laminated composites by laser melting deposition

TC4-(TiB + TiC)/TC4 composites with the laminated structure were successfully prepared by laser melting deposition, and the interlaminar structure and the microstructure after annealing were observed. The result shows that Boron (B) and Carbon (C) elements was diffused, and the interlayer transition layers were formed between TC4 and (TiB + TiC)/TC4 layers in the laminated composite due to the laser repeated remelting. In-situ reinforcement phase (TiB + TiC) forms a three-dimensional quasi-continuous network (3DQCN) structure, which enhances the TC4-(TiB + TiC)/TC4 composites material. After annealing at 800 °C, 900 °C, and 1000 °C, the equiaxed level of TC4-(TiB + TiC)/TC4 laminated composite got improved demonstrably. In addition, the microhardness of TC4-(TiB + TiC)/TC4 laminated composite reached the maximum(438.2HV_0.2) at 1000 °C, which was almost improved by 11.6%. It is worth noting that the volume fraction and grain size of the grain boundary α phase arise with the increase of annealing temperature.