When viscoelastic and viscoplastic materials are subjected to a constant stress for a period of time, a time-dependent deformation occurs, known as creep. During a nanoindentation test, creep is observed as an increase in depth of the indenter probe held at a constant force as a function of time. Accuracy of creep data at the nanoscale is highly dependent on nanoindentation system’s thermal stability, precise control of applied force, and sensitivity in measuring small changes in probe displacement. Nanoindentation allows quantitative creep characterization of thin films, individual microstructures, functionally graded interfaces, and small surface structures.
Bruker’s unique electrostatic transducer technology provides quantitative and reliable creep characterization at the nanoscale. In contrast to other electrical current-based actuation techniques that suffer from thermal drift, Bruker’s electrostatic actuation produces negligible heat when in operation. Combined with industry-leading noise floors and ultra-fast feedback control algorithms provided by Bruker’s Hysitron Performech Advanced Control Technology, creep testing can be performed on a scale not possible utilizing other technologies. Additionally, nanoDMA III incorporates unique reference frequency algorithms to provide drift-free creep measurements over long time periods. nanoDMA III used in conjunction with one of Bruker’s temperature control stages enables accurate nanoscale creep characterization at non-ambient temperatures and determination of creep activation energies.