Titanium/Titanium Carbide (Ti/TiC) composites with 20, 40 and 60 vol% of TiC powders were deposited on Ti-6Al-4V substrates using a laser-directed energy deposition method. The bulk relative densities exceeding 99% were achieved in the deposits. The evolution of microstructures and local chemical compositions in the deposits under rapid melting and solidification were analyzed using X-ray diffraction, electron probe micro-analyzer and scanning electron microscopy. Assessment of mechanical integrity of the deposits involved microhardness, tensile testing and fractography. The deposition process resulted in defect-free deposits with 20% TiC. However, cracks were observed originating from the substrate/deposit interface in the 40% and 60% TiC deposit. The L-DED process caused only partial dissolution of the initial TiC particles and the amount of undissolved particles in the deposited matrix increased with increasing TiC volume fraction in the initial powder feedstock mixture. A non-stoichiometric TiC_0.55 compound was found to form during solidification. The solidified product in the deposits included dendritic and equiaxed TiC_0.55 precipitates homogeneously distributed in the matrix. Micro-hardness measurements indicated that hardness values increased monotonically with TiC content in the deposit. On the other hand, a gradient Ti/TiC composite with composition ranging between 20% and 60% TiC did not develop any growth cracks suggesting an efficient processing route for synthesizing MMCs with high volume fraction of brittle ceramic reinforcements. It was found that pre-existing cracks in the TiC used in the starting feedstock played a key role in the mechanical integrity of the deposits. This observation suggests that the mechanical performance of the Ti/TiC composite deposits can be improved using techniques that promote complete dissolution of the original TiC.

使用激光定向能量沉积方法将钛/碳化钛 (Ti/TiC) 复合材料与 20、40 和 60 vol% 的 TiC 粉末沉积在 Ti-6Al-4V 基材上。在沉积物中实现了超过 99% 的体积相对密度。使用X射线衍射、电子探针显微分析仪和扫描电子显微镜分析了在快速熔化和凝固条件下沉积物中微观结构和局部化学成分的演变。沉积物机械完整性的评估包括显微硬度、拉伸试验和断口分析。沉积过程产生了含有 20% TiC 的无缺陷沉积物。然而，观察到裂纹起源于 40% 和 60% TiC 沉积物中的基材/沉积物界面。在大号-DED 过程仅导致初始 TiC 颗粒的部分溶解，沉积基质中未溶解颗粒的数量随着初始粉末原料混合物中 TiC 体积分数的增加而增加。发现在凝固过程中形成了非化学计量的 TiC _0.55化合物。沉积物中的固化产物包括枝晶和等轴 TiC _0.55沉淀均匀分布在基体中。显微硬度测量表明硬度值随着沉积物中 TiC 含量的增加而单调增加。另一方面，成分范围在 20% 到 60% TiC 之间的梯度 Ti/TiC 复合材料没有产生任何生长裂纹，这表明合成具有高体积分数的脆性陶瓷增强材料的 MMC 的有效加工途径。发现用于起始原料的 TiC 中预先存在的裂纹对沉积物的机械完整性起着关键作用。这一观察结果表明，使用促进原始 TiC 完全溶解的技术可以改善 Ti/TiC 复合沉积物的机械性能。