Acoustic microscopy measurement of elastic constants and massdensity

摘要

A method is presented to determine the elastic constants and thenmass density of isotropic and anisotropic solids and anisotropic thinnfilms. The velocity and attenuation of leaky surface acoustic wavesn(SAWs) have been obtained for specified propagation directions from V(z)ncurves measured by line-focus acoustic microscopy (LFAM). Thenexperimentally obtained velocities have been compared to velocitiesnobtained from a measurement model for the V(z) curve which simulates thenexperiment. Since the measured and simulated V(z) curves have the samensystemic errors, the material constants are free of such errors. For annisotropic solid, Young's modulus E, the shear modulus G and the massndensity Ρ have been determined from the leaky Rayleigh wave velocitynand attenuation, measured by LFAM, and a longitudinal wave velocitynmeasured by a pulse-echo transit-time technique. For a cubic-crystallinensolid, the ratios of the elastic constants to the mass density (c11n/Ρ, c12/Ρ, c44/Ρ) have beenndetermined from the directional variation of measured SAW velocities,nusing a preliminary estimate of Ρ. The mass density Ρ hasnsubsequently been determined by additionally using the attenuation ofnleaky SAWs in crystal symmetry directions. For a cubic-crystalline thinnfilm deposited on a substrate, the elastic constants and the massndensity (c11, c12, c44, Ρ) of thenfilm have been determined from the directional variation of the measurednSAW velocities, and a comparison of the corresponding attenuationncoefficient with the measured attenuation coefficient has been used tonverify the results