Ultrasonic characteristics of porous Zr55Cu30Al10Ni5 bulk metallic glass fabricated by spark plasma sintering

The elastic and damping behaviors of porous Zr55Cu30Al10Ni5 glassy alloy fabricated by a spark plasma sintering (SPS) process were investigated as a function of porosity at room temperature. Bulk modulus (K) and Lamè parameter (λ) decrease in a parabolic manner, while Young’s (E) and shear (G) moduli decrease gently with an increase in porosity. The order of K, λ, E, and G, which is monopolistically characteristic of nonporous glassy alloys, changes to the order of E, K, G, and λ, reflecting a crystalline-like deformation mode which is further confirmed by combining the decrease in Poisson’s ratio with the increase in G/K and E/K ratios up to 34.4% porosity. An increase in porosity induces frequency convergence for longitudinal wave, as well as increases in the longitudinal and shear attenuation coefficients.