Acoustic characteristics of Ni-Nb-Zr-H glassy alloys by ultrasonic shear waves

The propagation characteristics of shear horizontally polarized (SH) waves passing through (Ni₄₂Nb₂₈ Zr₃₀)_100-xH_x (x = 0-15.2) glassy alloys were investigated as a function of hydrogen content. With an increase in hydrogen content, the propagation time and main frequency of the receiving waves show increase and decrease, respectively, indicating expansion in average atomic distance which comes from solution of hydrogen. In sharp contrast to crystalline alloys, the decrease in damping ratio and the delay in phase with increasing hydrogen suggest a strong settlement of hydrogen into four-coordination sites surrounded tetrahedrally by four Zr atoms and the resulting increase in dynamic elasticity, respectively.