Physical properties of Zr₅₀Cu_{40 - X}Al ₁₀Pd_x bulk glassy alloys

It was shown recently (Yokoyama et al. [9]) that the addition of a small amount of Pd to the Zr₅₀Cu₄₀Al₁₀ bulk glassy alloy (BGA) has a beneficial effect on fatigue-strength enhancement, where the composition Zr₅₀Cu₃₇Al₁₀Pd₃ behaved in a resonant-like way by showing the highest fatigue limit of 1050 MPa and the minimum Vickers hardness. We performed a study of the magnetic properties, the specific heat, the electrical resistivity and the hydrogen-diffusion constant for a series of compositions Zr₅₀Cu_{40 - x}Al ₁₀Pd_x (x = 0-7 at.%), in order to determine their physical properties and to check for the influence of the Pd content on these properties. The Zr₅₀Cu_{40 - x}Al₁₀Pd_x BGAs are nonmagnetic, conducting alloys, where the Pauli spin susceptibility of the conduction electrons is the only source of paramagnetism. The low-temperature specific heat indicates an enhancement of the conduction-electron effective mass m* below 5 K, suggesting that the Zr₅₀Cu_{40 - x}Al₁₀Pd_x BGAs are not free-electron-like compounds. The electrical resistivities of the Zr ₅₀Cu_{40 - x}Al₁₀Pd_x BGAs amount to about 200 μΩ cm and show a small, negative temperature coefficient (NTC) with an increase from 300 to 2 K of 4%. The hydrogen self-diffusion constant D in hydrogen-loaded samples shows classical over-barrier-hopping temperature dependence and is of comparable magnitude to the related icosahedral and amorphous Zr_69.5Cu₁₂Ni₁₁Al_7.5 hydrogen-storage alloys. No correlation between the investigated physical parameters and the Pd content of the samples could be observed.