A Study of the Room Temperature Anelastic Creep of Cu-Be

The future nanotechnology requires materials which are dimensionally and elastically stable within the nm-domain. Because of their elastic stability, Cu-Be alloys are often used for the fabrication of elastic force sensors (spring elements). Anelastic and viscous creep limit the precision of such sensors. Therefore we have studied the anelastic and viscoelastic relaxations of Cu-Be using laser heterodyne interferometery. This method allows to measure flexural displacements as small as 0.1 nm. Our measurements revealed that the anelastic creep of Cu-Be is influenced by the microstructure of the bulk sample as well as the surface condition. The observed influence of the surface on the anelastic creep suggests that the surface dislocation density controls the anelastic relaxation.