Assessment of the effect of different forms of Inconel 625 alloy feedstock in Plasma Transferred Arc (PTA) additive manufacturing

Additive manufacturing (AM) is an emerging fabrication technology that offers a faster, versatile, flexible, easily customizable, and cheaper production path compared to conventional manufacturing. Different AM techniques are differentiated by how the material is made available and melted in each layer. Plasma Transferred Arc (PTA) is a promising AM technique due to its superior energy efficiency relative to laser-related processes. PTA enables the processing of materials in both powder and wire forms. Recent evidence suggests that the characteristics of the feedstock significantly affect the final microstructure and mechanical properties of the deposit. This study conducts a detailed analysis of the effects of feedstock form using PTA to create multilayers with wire and powder forms of Inconel 625 alloy. It examines the specific features of each feedstock for processing and explores their relationship with the characteristics of the deposited multilayers. The analysis involved confocal microscopy, scanning electron microscopy, X-ray diffraction, and micro-hardness profiling of powder plus arc and wire plus arc multilayers. The results demonstrate that the microstructure and mechanical properties of multilayer components are influenced by the choice of feedstock, primarily due to the differing parameters required for their processing.