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 crackfree 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, loadbearing 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.