Low-temperature dependence of elastic moduli and internal friction for glassy Pd42.5Ni7.5Cu30P20
M. Fukuhara a; T. Wada a; A. Inoue a; F. Yin b
a Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
b National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047, Japan
Abstract
Longitudinal and transverse wave velocities, eight kinds of elastic parameters, and the dilational and shear internal friction of Pd42.5Cu30Ni7.5P20 glassy alloy have been simultaneously measured as a function of temperature in the range from 77 to 373 K, using an ultrasonic pulse method. Monotonic decreases in the Young and shear moduli and in the Debye temperature in the range above 77 K are interpreted in terms of thermal relaxation of squeezed free volumes, accompanied by an increase in the interatomic distances, the appearance of entropy elasticity, and a uniaxial volume-preserving deformation. A 272-K valley of dilational friction seems to correspond to a topological change associated with electron-phonon coupling caused by the release of strains.
Keywords: glassy alloy; low temperature; elastic modulus; elasticity; internal friction; metallic glasses; ultrasonics