18Ni300 maraging steel with different TiC contents (0−10 wt.%), for the first time, have been fabricated by a direct laser deposition (DLD) technique. The microstructure and properties of the as-deposited and heat-treated samples have been carefully investigated. The obtained results show that the original 18Ni300 maraging steel exhibits extremely fine cellular microstructure with an average diameter of 3.7 μm, composed of martensite (M) and Ti₂N. In contrast, the microstructure of the TiC-reinforced composites is significantly refined, in which the volume fraction of TiC formed with different morphologies varies with the TiC addition content. However, some cracks exist in the composite sample with the TiC addition up to 10 wt.%. The average microhardness of the as-deposited samples increases initially and then decreases with increasing TiC content, and the maximum microhardness (444 HV_0.2) is obtained after adding 5 wt.% TiC. In addition, the sample with 5 wt.% TiC has been experienced a solution treatment at 850 ℃ for 1 h and then a subsequent aging treatment at 500 ℃ for 3 h. A number of nano-precipitates Ni₃(Mo,Ti) and a few austenite are formed, which are dispersed in the martensite matrix after the heat treatment. This results in a high microhardness of 576 HV_0.2 and a low wear rate of 1.37 × 10^-6 mm³/(N·m), compared with those of the TiC-free sample (368 HV_0.2 and 5.61 × 10^-5 mm³/(N·m)), respectively. The possible microstructural mechanisms accounting for the property changes of the TiC-reinforced 18Ni300 maraging steel have been discussed in detail.

首次通过直接激光沉积（DLD）技术制造了具有不同TiC含量（0-10 wt。％）的18Ni300马氏体时效钢。仔细研究了沉积和热处理样品的微观结构和性能。所得结果表明，原始的18Ni300马氏体时效钢表现出极细的泡孔组织，平均直径为3.7μm，由马氏体（M）和Ti _2组成。N.相反，TiC增强复合材料的微观结构得到了显着改善，其中以不同形态形成的TiC的体积分数随TiC添加量的变化而变化。但是，复合样品中存在一些裂纹，其中TiC添加量高达10 wt。％。沉积态样品的平均显微硬度首先随着TiC含量的增加而增加，然后降低，并且在添加5 wt％的TiC之后获得最大的显微硬度（444 HV _0.2）。此外，TiC含量为5 wt。％的样品在850℃下固溶处理1 h，然后在500℃下进行时效处理3 h​​。多种纳米沉淀物Ni ₃（Mo，Ti）和少量奥氏体形成，它们在热处理后分散在马氏体基体中。与不含TiC的样品（368 HV _0.2和5.61×10 ^-5  mm ）相比，这导致了576 HV _0.2的高显微硬度和1.37×10 ^-6  mm ³ /（N·m）的低磨损率。³ /（N·m））。详细讨论了可能的微结构机制，解释了TiC增强的18Ni300马氏体时效钢的性能变化。