アームコ鉄のフェライト粒子平均直径が超音波減衰に与える影響について

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It is known that the ultrasonic attenuation changes by microstructure and grain size of polycrystalline metals. Generally, it is considered that the mechanisms that cause loss in metals are mainly elastic hysteresis, forced motion of dislocations and scattering by the grains. Several authors have reported that ultrasonic attenuation of polycrystalline metals is fit by the equation α=A_1f+A_2f^2+A_4f^4 Here α is ultrasonic attenuation, f is ultrasonic frequency, A_1, A_2 and A_4 are the coefficients. The component proportional to the frequency shows the presence of elastic hysteresis (including motion of magnetic domain wall in ferromagnetic metals). The second term proportional to the second power of frequency is indicative of the motion of dislocation (in this study, the term is negligibly small). The last term proportional to the forth power of frequency id Rayleigh scattering loss. The theory of Mason and McSkimin gives the following form for A_4 on longitudianl wave when α is neper/cm : [numerical formula]. where T-volume of grain, v=velocity of the ultrasonic wave, K=average effective elastic modulus over all directions for propagating the ultrasonic wave in a given direction in a crystallite, ΔK=difference of the effective elastic modulus from its average as function of direction and <(ΔK/K)^2>_<av>=average of the fraction over all directions in the crystallite (ΔK/K)^2. Lifshits, Parkhomovskii and other authors also give the same form as above for A_4 which is proportional to the third power of train diameter D. Therefore, we prepared five samples of armco iron with different ferrite grain size. Transducer was X-cut quartz disk 2 cm in diameter for longitudinal wave measurement. The attenuation was measured at the 1, 3 and 5 megacycles per second. Theoretical and experimental results were compared with respect to the attenuation of Rayleigh scatter in specimens.
社団法人日本材料学会の論文
1963-11-15

アームコ鉄のフェライト粒子平均直径が超音波減衰に与える影響について

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