Microstructure, hardness, and wear properties of hot-press sintered Cr3C2/ Ni3Alcomposites containing Cr3C2 particles of different sizes

In this study, Cr3C2/Ni3Al composites containing Cr3C2 particles of different sizes were prepared via hot-press sintering. Subsequently, the effects of the size of the added Cr3C2 particles on the microstructure, hardness, and tribological properties of the Cr3C2/Ni3Al composites were investigated. The results showed that the Ni3Al powder and Cr3C2 particles in the composites exhibited obvious interdiffusion interactions during the hot-press sintering process and formed a new diffusion phase with an M7C3 (M = Cr, Fe, and Ni) structure in the Cr3C2/Ni3Al composites. In addition, the diffusion effect in the composites with small Cr3C2 particles was full, the proportion of the M7C3 (M = Cr, Fe, and Ni) diffusion phase in the composites was greater, and the solid-solution strengthening effect of the matrix phase was evident. The hardness of the Cr3C2/Ni3Al composites was noticeably higher than that of the Ni3Al alloy because of the combination of particle, solid-solution, and refined crystalline strengthening effects. The composite with 5 mu m Cr3C2 particles displayed the maximum hardness (56.3 HRC) and best wear resistance. The wear mechanism results indicated that the carbide particles in the composites improved the hardness, carried the load, and blocked the movement of abrasive particles, effectively protecting the matrix from wear. However, when the added Cr3C2 particles were too large, the weak interfacial bond between the chromium carbides and the matrix phases in the composites allowed the chromium carbides to easily crack and fall off, which decreased the wear resistance.