On the Room-Temperature Creep Behavior and Its Correlation with Length Scale of a Litao3 Single Crystal by Spherical Nanoindentation

摘要

Relying on nanoindentation technology, the room-temperature creep behavior of a LiTaO single crystal in the typical orientation (01 2), i.e., Y-42° plane was investigated. Three kinds of spherical tips with the radii of 0.76, 2.95 and 9.8 μm were respectively applied to detect nanoindentation length scale effect on creep deformation at both elastic and plastic regions. Superficially, both creep displacement and rate were nearly linearly increased with increasing holding depth and independent of tip size, which could be ascribed to the simultaneously enlarged holding strain and deformation volume beneath the indenter. At a similar holding strain, creep deformation, i.e., creep strain and strain rate were more pronounced under smaller spherical tips. Strain rate sensitivities of creep flows under different spherical tips and holding strains were also estimated. The potential room-temperature creep mechanism of LiTaO under high shear compression stress was discussed.