2835 Elastic Properties of Pd-based Bulk Metallic Glass Studied by Resonance Ultrasound Spectroscopy

Because of its superior mechanical properties in addition to complete isotropy, bulk metallic glasses (BMGs) are potential candidate material for the future applications to micro-electro-mechanical systems (MEMS). In the present work, we have investigated ambient temperature elastic constants of Pd_<78>Cu_6Si_<16> bulk metallic glass (BMG) by ultrasound spectroscopy techniques. Free vibration resonance spectra have been successively obtained both by resonance ultrasound spectroscopy (RUS) and electromagnetic acoustic resonance (EMAR), suggesting that the BMG has low internal friction in the MHz frequency range. The BMG show remarkably low bulk to shear modulus ratio (〜0.18) compared with previously studied Pt-based (〜0.3) and Cu-based (〜0.28) BMGs suggesting that it has good fragility as well as ductility. The relatively high acoustic Debye temperature Θ_D and glass transition temperature T_g of the BMG suggest high thermal stability about the devitrifications of the system such as crystallization. Present results suggest that the BMG is one of the best systems as a standard material to calibrate micro-sized material testing equipments.