Effect of TiC and Magnetic Field on Microstructure and Mechanical Properties of IN738 Superalloy Processed by Selective Laser Melting

Modifying the microstructure of the IN738 superalloy increases the working efficiency of gas turbine blades. In this study, the microstructure of IN738 superalloy processed by selective laser melting was improved by applying a magnetic field and adding TiC nanoparticles. The results show that the application of a magnetic field by crushing the solidifying grains and the addition of TiC by creating places for the heterogeneous nucleation of the melt causes a remarkable expansion of the equiaxed grains. However, the simultaneous application of a magnetic field and TiC nanoparticles significantly reduces the grain size, grain aspect, and, consequently, the crack density and porosity. Also, the results showed that with the reduction of grain ratio, high-angle grain boundary and grain boundary length density increase dramatically, which results in a decrease in the concentration of elements and phases sensitive to cracking in grain boundaries. The increase in the volume fraction and the reduction in the γ' size were other effects of adding TiC and the external field, which significantly improved the creep and wear behavior. So, with the expansion of the equiaxed region, the hardness increased, and the wear resistance increased through the delay in the transition from the elastic area to the plastic area during the wear test.