Slurry erosion resistance of Al18B4O33 whisker-reinforced AC4C Al alloy matrix composites

Abstract

Abstract Slurry erosion resistance of as-cast and T6-treated 19.5 vol.% Al 18 B 4 O 33 whisker reinforced AC4C Al composites and AC4C Al alloys was investigated at room temperature. Erosion tests were performed with slurry having jet velocity range 6.4–15.2 ms −1 and at normal impact angle, and a sand concentration of 20 wt%. Scanning electron and optical microscopy were used to characterize the microstructure of the materials and the mechanisms of the slurry erosion. The results indicated that the slurry erosion characteristics of the materials were affected by the particle velocity and material properties. At low slurry velocities, the erosion resistance for the MMCs was improved as a result of whisker addition. However, steady-state rate was found to increase with the addition of whisker to the matrix alloy at high slurry velocities. Age-hardening (T6) treatment was not effective in improving the erosion resistance of the composites. High erosion rate in the whisker reinforced MMCs can be attributed to reduced fracture strain. In addition to plastic deformation, for the composites, surface fracture and dislodgement of Al 18 B 4 O 33 whisker occurred under high-velocity slurry impact conditions. By considering the material removal processes, a simple rationalization of the inverse dependence of slurry erosion rate on He f was obtained.