Structural characterization and nanoindentation studies on mechanical properties of spark plasma sintered duplex stainless steel nanocomposite

Nano-sized titanium nitride (TiN) powders were used as reinforcements for the fabrication of duplex stainless steel (SAF 2205) via spark plasma sintering (SPS) route. Optimized parameters of 1150 °C temperature, 100 °C/min heating rate, 50 MPa pressure and 15 min holding time were utilized for sintering of the SAF 2205-TiN composite. SEM equipped with an EBSD and TKD detectors were used to gain insight into sintered composite microstructures and grain boundary character. XRD was used to study crystallinity and phase transformation. The discrete mechanical properties of ferrite/austenite grains and grain boundaries were studied using nanoindentation technique. The addition of TiN nanoparticles resulted in decrease of the α-Fe peaks with principal planes shifting from α-Fe (110) to γ-Fe (111). The EBSD confirmed that the addition of TiN nanoparticles to duplex stainless steel could initiate and advance ferrite to austenite phase reverse transformation. The TKD confirmed that nanosized nitrides are concentrated at the ferrite/austenite interface. The nanoindentation studies showed that the nano-hardness (H), elastic modulus (E), plasticity index (Ψ), and anti-wear properties were improved with the TiN nanoparticle addition from 0 to 8 wt%.