PSI - Issue 50

V.N. Kostin et al. / Procedia Structural Integrity 50 (2023) 151–154 V.N. Kostin et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 1. Dependences of the magnetostriction of cold-deformed and annealed nickel on annealing temperatures measured by the remote induction sensor method λ magn (a) and laser interferometry λ if (b)

The average graph for two series of measurements using laser interferometer Polytec PSV-500-HV is shown in Fig. 1b, the error is determined by the maximum and minimum values. Based on the analysis of the graphs presented in Fig. 1a and Fig. 1b, a correlation dependence of the magnetostriction measured by two methods was constructed (Fig. 2). The square of the correlation coefficient is 0.95. For nickel typical annealing temperatures lie in the range of 400 –550 °C. Thus, at annealing temperatures lower than 400 °C the processes of return prevail: redistribution and decreas e in the concentration of point defects and dislocations. At higher temperatures recrystallization occurs and recrystallized phase grows in volume.

Fig. 2. Correlation of magnetostriction of nickel, measured by laser interferometry λ if and remote induct ion sensor λ magn

Authors propose the setup based on speckle interferometry method as an economical substitute of the laser vibrometer for the measurement of magnetostrictive characteristics. The measurement of the magnetostrictive characteristics, such as magnetostrictive sensitivity has a practical meaning, since in low fields the amplitude of the harmonic of the magnetoacoustic emission (MAE) signal with a frequency equal to the doubled magnetization reversal frequency is proportional to the linear magnetostrictive sensitivity (Kostin et. al., 2013, Serbin et. al., 2020). The setup is shown in Fig. 3. The laser (6) illuminates the end face of the sliding sample holder (8), which, due to the phenomenon of magnetostriction, exactly repeats the change in sample (2) dimensions. Thus, all points of the surface of the attachment end (scattering centers) move simultaneously in the same plane. A reflector (5) is present in the scheme of the speckle-interferometric setup to register the change in the linear dimensions of the sample.