Determination of the elastic properties of some coated materials by simulation of the analogue signal of the reflection acoustic microscope

We discuss in this work the elastic properties of monolayer materials (layer/substrate). We consider both cases of quick/slow and slow/quick systems. We calculate Young's modulus, shear modulus and Poisson's ratio of the following four systems: Cr/Fe, TiN/Fe, Al/Si and Al/SiC. We make it evident that the use of the simulated acoustic signal of the reflection acoustic microscope yields to the determination of the wave propagation velocity of different modes in the layer/substrate according to the frequency and the thickness of the layer. We demonstrate that Victorov relation is not applicable in this case. A new method, that we called ‘method of homogenization’ is proposed to resolve the problem of dispersion.For the considered materials, the calculations have been carried out in a large range of frequencies (50 MHz–3.5 GHz) and coating layer thickness (0.5–150 μm). We show that for the studied materials the elastic constants take the values of the material layer beyond a thickness of 30–40 μm.