CM247LC superalloy has high cracking sensitivity, which limits its wide application in additive manufacturing field. In this work, we propose to improve the cracking sensitivity of CM247LC alloy by adding nanoscale TiC particles. The TiC/CM247LC nanocomposite with low crack defects was successfully prepared by selective laser melting (SLM), and the cracking inhibition behavior and strengthening mechanisms were systematically studied. The results show that the optimal SLM processing of TiC/CM247LC nanocomposite is scanning spacing of 80 μm, scanning speed of 1000 mm/s and laser power of 200 W. Under this processing, the defects ratio of the nanocomposite is 1.95%, which is about 2% lower than that of CM247LC, and the ultimate tensile strength and yield strength were obviously improved. The TiC particles can refine the nanocomposite grain and reduce local strain concentration, and the uniformly distributed TiC particles at grain boundaries also can strengthen grain boundaries, which may be the main reasons for the low crack defects of the nanocomposite. Load-bearing strengthening of particles and Orowan strengthening are the main strengthening mechanisms of the TiC/CM247LC nanocomposite.

CM247LC高温合金开裂敏感性高，限制了其在增材制造领域的广泛应用。在这项工作中，我们建议通过添加纳米级 TiC 颗粒来提高 CM247LC 合金的开裂敏感性。采用选择性激光熔化（SLM）方法成功制备了低裂纹缺陷的TiC/CM247LC纳米复合材料，并系统研究了裂纹抑制行为和强化机制。结果表明，TiC/CM247LC纳米复合材料的最佳SLM工艺为扫描间距为80 μm，扫描速度为1000 mm/s，激光功率为200 W。在此处理下，纳米复合材料的缺陷率为1.95%，即比CM247LC低2%左右，极限抗拉强度和屈服强度明显提高。TiC颗粒可以细化纳米复合材料晶粒，降低局部应变集中，而均匀分布在晶界的TiC颗粒也可以强化晶界，这可能是纳米复合材料低裂纹缺陷的主要原因。颗粒的承载强化和Orowan强化是TiC/CM247LC纳米复合材料的主要强化机制。