High temperature oxidation behavior and characterization of DMLS fabricated Ni based superalloys

Abstract

Direct metal laser sintering (DMLS) is a type of powder-based additive manufacturing process in which the fabrication of components is done in a layer by layer system with melting and solidification of powder (raw material) employing a laser heat source. The objective of the present research is to analyze cyclic oxidation behaviour of DMLS fabricated Nickel based superalloy i.e. IN 625 and IN 718 in the air at 700 °C. Cyclic oxidation was carried out in a silicon carbide furnace for fifty cycles and one cycle involves heating of the specimen for 1 h in the furnace at a temperature of 700 °C followed by 20 min of cooling in the air at room temperature. The oxidation kinetics was evaluated by measuring weight change after every cycle with the implementation of the thermogravimetric technique. Evaluation study of oxidation products was done by using charcterization techniques i.e. X-ray diffraction, scanning electron microscopy and X-ray mapping. The IN 625 proved to have better oxidation resistance than IN 718 under cyclic oxidation.