Elastic Properties of Cu-Based Bulk Metallic Glass around Glass Transition Temperature
Temperature dependent elastic constants Cij(T) of Cu60Hf30Ti10 bulk metallic glass (BMG) have been investigated in a MHz frequency range using electromagnetic acoustic resonance (EMAR) up to 823 K. At room temperature, the BMG showed high Poisson’s ratio ν arising from low shear modulus G compared with that of constitutive crystalline elements. With increasing temperature, G showed usual linear temperature dependence while it suddenly drops around glass transition temperature, Tg. Within a framework of quasiharmonic approximation, Grüneisen parameter γ around Tg is estimated to be 10. This extremely large γ indicates the high anhramonicity of long wavelength limit acoustic mode phonon in the supercooled liquid state. The unusual elastic behavior can be interpreted on the basis of heterogeneous microstructure.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
R. Tarumi et al., "Elastic Properties of Cu-Based Bulk Metallic Glass around Glass Transition Temperature", Materials Science Forum, Vols. 539-543, pp. 1932-1936, 2007