Surface modification of IN713 LC superalloy with Metco 204NS by laser surface alloying

Abstract

Abstract Ceramics are one of the best engineering materials for coating gas turbine blades. In this study, the Metco204NS ceramic coating (Zr2O + 8%Y2O3) was applied by the laser surface alloying (LSA) method on IN713 LC nickel-based superalloy. To influence the heat input on the structure of the ceramic coating and its substrate, and as well as the rejuvenated zone (RZ), different variables were used in LSA. The results showed that with an increase in heat input by the laser, the sensitivity to liquation cracks in the heat affected zone and solidification cracks in the RZ decreases. The most important reason for this was the increase in backfilling by the molten metal due to its high fluidity. However, with increasing heat input, the hardness increased due to the reduction of the distance between the dendrites. Solidification rate (R) and temperature gradient (G) were identified as the most important microstructure controlling factors in the RZ. So, with increasing the heat input and thus decreasing G and R, the tendency of the structure to change from cellular to columnar and then equiaxed increased. The uniform and homogeneous coating of Metco 204NS significantly increased the wear resistance of IN713 LC superalloy. The higher hardness and wear resistance of melted Metco 204NS coating material relative to the RZ and the base metal was due to the presence of very hard Zr2O and Y2O3 particles in Metco 204NS and the reduction of grain size.