Cracking inhibition behavior and the strengthening effect of TiC particles on the CM247LC superalloy prepared by selective laser melting

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.