Non-destructive characterization of laminated composite films by laser ultrasonic technique

The method of using pulsed surface acoustic waves generated by pulsed laser to evaluate properties of layered films, such as Young's modulus, density and thickness etc., has been investigated. A novel fcc/Ll(2) metal (Ni)-int ermetallic (Ni3Al) composite film is characterized, in which the Fourier tr ansform of the pulsed surface acoustic wave signals yield the dispersion cu rve of the surface wave velocity spectrum By theoretical simulation, the Yo ung's modulus about 284 GPa, and density about 7.650 g/cm(3), as well as th e thickness about 140 mum of the composite film have been obtained. For com paring, we also using this method to detect the single Ni3Al film and obtai n its Young's modulus of 369 GPa. The Young's module of the laminated compo site film and the intermetallic (Ni3Al) film are much larger than that of N i. From these results we can infer that the laminated Ni-Ni3Al film is expe cted to have better mechanical properties.