Thermal shock resistance of a NiCrAlY-coated Alloy 625 system produced by laser powder bed fusion

Additive Manufacturing offers an innovative route for producing high-quality parts in various fields. A bi-material system, consisting a NiCrAlY bond coat deposited onto Ni-based Alloy 625 substrate, was manufactured by laser powder bed fusion (LPBF). Test samples were prepared and included sol-gel ceramic ZrO2(Y2O3) top coats as well specific grain boundary serration (GBS) heat treatment promoting high temperature resistance. These specimens subjected to very severe thermal shock cycles between 950 °C 300 °C, characterized steep heating air quenching rates state-of-the-art burner rig designed render gas turbine conditions, their integrity compared. While LPBFed coatings relatively spared from degradations due shocks, exhibited clear spallation. Poor bonding particularly experienced the GBS unavoidable formation therein of surface oxides. Numerous cracks detected within coats, both tested pre-cycled as-built ones, which suggested dominant role LPBF process known generating residual stress. Heat treated nearly no cracking. Hardness found significantly increase result exposure during cycling attributed precipitations. The fully recrystallized microstructure specimens, on other hand, more stable. present study completes series investigations demonstrating great potential manufacturing excellent structural components means opposed constraining conventional routes.