In-situ oxygen-regulated heterogeneous FeCrNi MEA via laser cladding: enhancement of tribo-corrosion and corrosion resistance

In this study, the FeCrNi-X (X = Ti, TiO₂) composite coating was prepared via laser cladding to investigate the regulatory mechanisms of micro‑oxygen alloying on microstructure, tribological properties and corrosion resistance, thereby advancing their application and development in manufacturing processes, contributing to increased production efficiency and improving component performance. The result show that partially dissolved oxygen atoms inhibited lattice migration through the solute drag effect, while in-situ formed oxides and residual TiO₂ acted as heterogeneous nucleation sites, leading to the pinning effect. The combined effects cause the multiphase heterogeneous structure formation, consisting of BCC and FCC phases and dispersed oxides, which effectively suppresses grain boundary migration and coarsening, while concurrently hindering dislocation propagation during deformation. As a result, the hardness increased to 466.14 HV_0.5, which is 1.56 times that of the FeCrNi alloy. The FeCrNi-TiO₂ coating benefits from the pre-oxidation effect, which promotes the preferential formation of a density oxide layer that effectively prevents further oxidation. The I_corr values in salt and acid solutions (2.93 × 10⁻⁵ and 1.65 × 10⁻⁵ A/cm²) are only 0.539 and 0.245 times those of the FeCrNi-TiO₂ alloy, respectively. Moreover, wear debris produced under tribo-corrosion coupling tends to oxidize, forming hard oxides that contribute to friction and increase interfacial shear resistance in acidic corrosion environments. In contrast, wear debris formed in salt corrosion environments mainly comprises low-hardness chlorides, which serve as solid lubricants. This research aims to systematically investigate the enhancement mechanisms of micro‑oxygen on the wear and corrosion resistance of FeCrNi alloy, thereby advancing their application and development in manufacturing processes, contributing to increased production efficiency and improving component performance.