Application of Microacoustical Technique to Study Elastic Properties and Microstructure of New Generation of Bulk Metallic Glasses

Abstract

Elastic properties of bulk metallic glass (BMG) Pd₃₉Ni₁₀Cu₁₀P₂₁ have been studied basing on sonic velocity data analysis. Different states of the Pd₃₉Ni ₁₀Cu _{1 o}P₂₁ system (glassy state, super-cooled liquid (SCL) and re-crystallized states) were obtained by annealing of the samples at different temperature near the glass transition and onset crystallization temperature. Microacoustical technique has been applied to measure local values of longitudinal and transverse elastic wave velocities and their distribution over a specimen body. Finally sonic velocities C_L and C_T, density p, bulk K and shear G elastic moduli were measured for different states of Pd₃₉Ni ₁₀Cu ₁₀P₂₁ BMG. It has been shown decreasing values of p, C_L and K as temperature. For the re-crystallized state ultrasonic measurements were performed by low-frequency flat transducer because of high ultrasonic attenuation in this case. Acoustic images (C-scans) evidence occurrence of rough-grain microstructure at this state. It is assumed the rough granular structure with particles size 70-80m is characteristic for re-crystallized state of BMG.