The formation of ripples on pure Al and Al-12Si alloy surfaces was inv
estigated. Sharp angular Al2O3 and spherical glass beads were used as
erodent particles accelerated in an air-blast type system. The experim
ental variables were erodent particle shape, angle of impact, and abra
sive particle mixture. Scanning electron and optical microscopy used t
o study the morphology of impacted surfaces showed the well-developed
ripple formation on Al-12Si with beads used as abrasive. As the fracti
on of Al2O3 sharp particles mixed with glass beads was increased, the
ripple formation on Al-12Si diminished. An investigation of the surfac
e morphology of the eroded samples provided evidence for a mechanism o
f ripple formation based on material displacement instead of material
removal.