Wear mechanism of Cr₃C₂/Ni₃Al composites showing excellent wear resistance

The Ni₃Al intermetallic compound is considered an excellent wear-resistant material. The addition of Cr₃C₂ particles can further improve the wear resistance of Ni₃Al-based alloys. In order to elucidate the wear mechanism of Cr₃C₂/Ni₃Al composites improved by the Cr₃C₂ strengthening phase, Ni₃Al-alloy and Cr₃C₂/Ni₃Al composites were prepared by the hot isostatic pressing process in this study. The mechanical properties and wear resistance of each phase in the Ni₃Al-alloy and Cr₃C₂/Ni₃Al composites were investigated using a nano-indentation instrument and a pin-on-disk friction and wear tester, respectively. The worn surface morphologies and the hardness of the subsurface layer under the worn surfaces of the Ni₃Al-alloy and Cr₃C₂/Ni₃Al composites were determined by a scanning electron microscopy (SEM) and a nano-indentation instrument. The results indicate that the hardness of the matrix phase in the Cr₃C₂/Ni₃Al composites is significantly improved by the addition of Cr₃C₂ particles. The nano-hardness and the elastic modulus of each phase in the Cr₃C₂/Ni₃Al composites gradually increase from matrix phase through diffusion phase to hard core phase. The mechanical properties between the matrix, diffusion, and hard core phases in the Cr₃C₂/Ni₃Al composites present a gradient transition. This kind of structure distribution is good for enhancing the wear resistance of Cr₃C₂/Ni₃Al composite materials. As for friction and wear conditions in this study, abrasive wear was the dominant wear mechanism, which occurred on the surfaces of the Ni₃Al-alloy and Cr₃C₂/Ni₃Al composites. The Cr₃C₂/Ni₃Al composites showed a good wear resistant property. The carbide-strengthening phase can block up the cutting action of the wear debris, reduce the interaction between the wear materials, and decrease the thickness of the subsurface layer and the size of the wear debris, resulting in improved wear resistance of Cr₃C₂/Ni₃Al composites.