Patent ID: 6691575
Filing Date: 2004-02-17
Classification: G01N

Abstract:
A method for material evaluation by acoustic velocity measurements, comprising the steps of:(a) preparing a plurality of acoustical physical constants determining materials with different nominal chemical compositions; (b) measuring one of the Curie temperature and lattice constant of each of said acoustical physical constant determining materials as a physical property, and calculating a true chemical composition D of said each acoustical physical constant determining material by use of a known relationship between said physical property and said chemical composition; (c) preparing, from said each acoustical physical constant determining material, substrates for determining desired acoustical physical constants; (d) measuring the acoustic velocities v (vLSAW, vL, vS), dielectric constants and density for said acoustical physical constant determining substrates of different chemical compositions, and determining elastic and piezoelectric constants as acoustical physical constants of said each acoustical physical constant determining material based on measured values of said acoustic velocities, dielectric constants and density; and (e) measuring the acoustic velocities of a material to be evaluated, converting the measured values to desired parameters based on said acoustical physical constants, and evaluating said material based on said parameters, wherein step (e) comprises: (e-1) calculating acoustic velocity vâ€² for a desired cut specimen plane of said material, for a desired propagation mode and for a desired propagation direction with respect to said true chemical composition D by a known method through use of said determined acoustical physical constants; (e-2) calculating a gradient g=&Dgr;vâ€²/&Dgr;D of the acoustic velocity vâ€² calculated in said step (e-1) with respect to said true chemical composition D; and (e-3) measuring the distribution of acoustic velocity vâ€³ for the specimen to be evaluated, and calculating the amount of change, &Dgr;Dâ€³=&Dgr;vâ€³/g, of the chemical composition by use of said gradient g calculated in said step (e-2).