| Abstract Scope |
Alloy 625+xTiB₂ (x = 1.25, 2.5, 3.75, 5.0 wt%) nanocomposites were successfully fabricated via suction casting. Their microstructural characteristics and thermal stability were investigated using thermodynamic simulations, X-ray diffraction, light and scanning electron microscopy, scanning-transmission electron microscopy, energy-dispersive X-ray spectroscopy, dilatometry, differential scanning calorimetry, Vickers hardness testing, dry-sliding wear tests, and oxidation analysis. The incorporation of TiB₂ nanoparticles significantly influenced the dendritic microstructure of Alloy 625. In the unmodified alloy, Nb-rich carbides and Laves phase were primarily located in the interdendritic regions. Upon the addition of TiB₂, the particles reacted with the molten matrix during suction casting, leading to the formation of new phases, such as (Mo, Cr, Nb)₃B₂ and MN. The TiB₂ additions enhanced the mechanical properties, increasing the hardness and wear resistance. Long-term annealing in Ar+0.25 wt% SO₂) confirmed the excellent thermal stability of the composite with exhibited a mass gain of less than 0.4 mg/cm². |