Microstructural characterization of Wcu composite deposition on mild steel fabricated via plasma transferred arc welding

Abstract

In this study, a tungsten‑copper (WCu) composite was successfully deposited on mild steel substrate using a novel technique—Plasma Transferred Arc (PTA) welding. Spherical W and Cu powders were employed, and the resulting microstructural characteristics on a mild steel substrate were thoroughly analysed. Key PTA process parameters were established and found to significantly influence microstructural evolution. Notably, iron (Fe) dilution from the base metal markedly altered the composite's microstructure, and grain boundary diffusion of Cu into the mild steel substrate was observed. The size and morphology of W powder were found to affect the homogeneity and porosity of the deposited layer. X-ray diffraction and EDS point analysis revealed the formation of a new intermetallic phase, Fe₇W₆, around W particles. For the first time, a new intermetallic phase FeW was also confirmed by point EDS analysis. The intermetallic phase Fe₇W₆ was further confirmed by transmission electron microscopy (TEM) diffraction, indicating its stability at room temperature. Higher hardness values of the intermetallic phase were compared to other phases present in the composite.