In the present study, a series of in situ TiB/Ti6Al4V composites were fabricated using selective laser melting. The formability, microstructure evolution and mechanical properties of the as-built samples added with different contents of TiB₂ were studied. It is found that the densification level is related to both the content of TiB₂ and laser energy density. The added TiB₂ reinforcement particle can spontaneously react with titanium and then form the TiB phase. The needle-like TiB phase tends to transform into dot-like particles with the decrease in energy density. Additionally, with the increase in TiB₂ content, the TiB phase is coarsened due to the increased nucleation rate and more reactions. The grain morphology is found to largely depend on the translational speed of solid–fluid interface determined by the temperature gradient and cooling rate. Also, the microhardness of the as-built TiB/Ti6Al4V composites is obviously improved. More interestingly, as the energy density increases, the microhardness of the as-built TiB/Ti6Al4V composites firstly increases and then decreases due to the synergy of grain size and different morphologies and distribution of TiB phases. The wear resistance of TiB/Ti6Al4V composites is far superior to that of Ti6Al4V alloy owing to the increased microhardness resulted from the uniform distribution of the hard TiB phase in the matrix.

中文翻译：

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原位TiB / Ti6Al4V复合材料的选择性激光熔化：可成形性，微观结构演变和机械性能

在本研究中，使用选择性激光熔化技术制备了一系列原位TiB / Ti6Al4V复合材料。研究了添加不同含量的TiB _2的样品的可成形性，微观结构演变和力学性能。发现致密化水平与TiB ₂的含量和激光能量密度有关。添加的TiB ₂增强颗粒可以与钛自发反应，然后形成TiB相。随着能量密度的降低，针状TiB相趋于转变成点状颗粒。此外，随着TiB ₂的增加当含量增加时，由于成核速率的增加和更多的反应，TiB相被粗化了。发现晶粒形态在很大程度上取决于由温度梯度和冷却速率决定的固-液界面的平移速度。而且，TiB / Ti6Al4V复合材料的显微硬度明显提高。更有趣的是，随着能量密度的增加，由于晶粒尺寸以及TiB相的不同形态和分布的协同作用，初生TiB / Ti6Al4V复合材料的显微硬度首先增加，然后降低。TiB / Ti6Al4V复合材料的耐磨性远优于Ti6Al4V合金，这归因于硬TiB相在基体中的均匀分布而提高了显微硬度。