Surface alloying of aluminum bronze with titanium in a nitrogen containing atmosphere using tungsten inert gas process

In this study, surface alloying of aluminum bronze was carried out using a Tungsten Inert Gas (TIG) heat source in a nitrogen-containing atmosphere, through pre-placing titanium sheet serving as the alloying element. The research followed a systematic approach involving TIG processing at different traversing speeds to control the heat input and resulting microstructures. A combination of optical microscopy, scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were employed to investigate the phase structures and microstructural features of the alloyed layers. Microhardness profiling was performed to evaluate the mechanical characteristics of the treated layers. Dry sliding wear tests were subsequently conducted using a pin-on-disc tribometer under normal loads of 5, 20, and 40 N against 52100 hardened steel as the discs. The alloyed layers exhibited a refined and homogeneous structure, containing AlCu 2 Ti intermetallic compounds and titanium nitride (TiN) dendrites. These structural modifications led to a substantial increase in the surface hardness, reaching values as high as 400 HV, which is approximately 2.7 times higher than that of the base material (148 HV). Furthermore, the wear rates of the surface treated sample with the highest hardness were reduced to 5 %, 15 %, and 20 % of those of the base material under the applied loads of 5, 20, and 40 N, respectively. These improvements were attributed to the combined effect of hard phase formation, and the development of protective tribological layers enriched with iron oxides during the wear process.