Microstructure, mechanical and tribological properties of Al0.3CrFeNiTi0.3-CaF2/BaF2 self-lubricating composite fabricated by spark plasma sintering

In this study, a bulk solid Al0.3CrFeNiTi0.3-CaF2/BaF2 (HEA-CaF2/BaF2) self-lubricating composite was successfully fabricated using spark-plasma sintering (SPS) method. The phase constitutions, microstructural features, and mechanical properties of the composite have been extensively characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), compression and nanoindentation tests. The composite exhibited superior mechanical properties at room temperature (RT), and excellent thermal-mechanical stability from RT to 600 °C. Additionally, the composite possessed superior anti-friction and anti-wear properties in a broad temperature range below 900 °C, particularly showing even much enhanced lubricating capacity than HEA-Ag composite in the medium temperature range of 300–600 °C. The dominant wear mechanism of HEA-CaF2/BaF2 composite was abrasion when temperature was RT-300 °C, while it changed to adhesion and oxidation when temperature reached 600–900 °C.