Fabrication and strengthening mechanism of crack-free nano-TiC reinforced IN738LC with enhanced mechanical properties by laser powder bed fusion.

IN738LC alloy has broad application potential in modern aerospace and energy industries due to its excellent high-temperature durability, excellent corrosion and fatigue resistance, however, its application has been greatly limited due to its high crack sensitivity. To address this challenge, this research proposes a method of incorporating TiC nanoparticles to mitigate cracks and enhance the strength of the nickel-based materials. The crack-free TiC-IN738LC materials were successfully fabricated using laser-powder bed fusion. The relationship between the processing parameters and processed quality was studied. The fracture morphology and mechanical properties of samples were analyzed and the strengthening mechanisms of nano-TiC particles were clarified. The results showed that volume energy density (VED) = 111.1J/mm3 is the optimal processing parameter with the laser energy 225W, scanning speed 750 mm/s, and 0.09 mm hatch distance. The effects of processing parameters were discussed in depth. Compared with the virgin IN738LC, the microhardness of TiC-IN738LC is improved by 20 %–40 %, and the tensile strength of TiC-IN738LC is enhanced by 5%–30 %, respectively, which indicates the significant strengthening effect of nano-TiC on IN738LC. The synergistic effect of fine grain strengthening, load-bearing strengthening and Orowan strengthening mechanisms was accounted for the performance enhancement. The research results provide an experimental reference for selecting the processing parameters of TiC-IN738LC.