Acoustically induced plastic deformation of conical microcrystals on copper surfaces

Abstract

Micron-size conical microcrystals have been cultured on a copper surface using the sputtering action of a 100 keV argon-ion beam. When subsequently exposed to an intense 26 kHz acoustic field the cones were found to bend. The bent forms were identical in appearance to the distorted forms reported from time to time for unvibrated cones. These observations lend support to our recent theory that spontaneous bending is due to slip driven by surface stress which is accommodated by a tendency towards adoption of a helicoidal minimal surface shape.