High Temperature Elastic Constants of Pd- and Zr-Based Bulk Metallic Glasses Studied by Electromagnetic Acoustic Resonance
Ryuichi TARUMI, Noritaka HAYAMA and Masahiko HIRAO
Abstract:Elastic constants Cij of Pd40Ni40P20 and Zr55Al10Ni5Cu30 bulk metallic glasses (BMGs) has been investigated by MHz frequency range electromagnetic acoustic resonance (EMAR) from ambient temperature to their glass transition point Tg. With increasing in temperature the BMGs show elastically plateau region in Cij(T) curves which is due to two competitive processes; elastic softening by anharmonicity and stiffening by structural relaxation. Significant elastic softening in Cij(T) curves was confirmed around Tg without any precursor phenomena. Our theoretical analysis revealed that elastic inhomogeneity can explain the characteristic elastic behaviors around Tg. Key Words:Bulk metallic glasses, Elastic constants, glass transition, mechanical stability, micromechanics analysis