Makoto Kurosawa

Eddy current evaluation of cast irons for material characterization

Abstract This study proposes a novel method for the evaluation of matrix structures of cast irons by means of eddy current (EC) evaluation. Experimental results of gray and ductile cast irons show that EC evaluation is sensitive to the difference of matrix structures obtained by microstructure observations. It was shown that relationship between percentage of pearlite in ductile cast iron and EC signals can be fitted by a functional dependence. Results of mechanical tests—Vickers hardness of specimens can also be predicted by means of EC evaluations.

Brillouin scattering from the soft optical phonon in the orthorhombic form of a K3Co1-xFex(CN)6 (x ≤ 0.03) crystal

The soft optical phonon in the two-layer orthorhombic form of a K3Co1-xFex(CN)6 (x≤0.03) single crystal has been reinvestigated using a (3+3)-pass tandem Fabry-Perot interferometer around the structural phase transition temperature. The soft phonon response can be well described using the phonon-relaxator coupled model. The soft phonon frequency ω∞/2π obeys the |T-T c±|1/2 law except in the vicinity of T c=82.5 ±0.1 K; (ω∞/2π)2=1.20×103(T-82.1) (GHz2) for T>T c and 4.55×103(83.0-T) (GHz2) for T<T c. The soft phonon-relaxator coupling constant increases linearly above the T c as the temperature decreases and the slope becomes steeper below T c. The relaxation time is longer than 40 ps and independent of temperature above T c, but becomes one order of magnitude shorter below T c. The Fe3+ defects seem to be responsible for these unusual temperature dependences.