The Detection of Magnetic Phase Transitions in ER-TM by Electromagnetic Acoustic Transducers

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Date
1998
Authors
Lin, C. M.
Dixon, S.
Edwards, C.
Palmer, S.
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Review of Progress in Quantitative Nondestructive Evaluation
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Abstract

The phases in magnetic materials can be studied ultrasonically. Magnetic phase transition points can be determined from discontinuities in ultrasonic velocity as a function of temperature. Conventionally this is done using piezoelectric transducers (normally quartz) pulsed with a tone burst generator. Very accurate velocity measurements are required as the change in velocity is typically 1 part in 104 [1]. A common problem experienced with contacting transducers is the fracturing of the acoustic couplant bond at low temperatures. Non-contacting acoustic techniques have no problems with bond failure, electromagnetic acoustic transducers (EMATs) can be used for measurements on rare earth magnetic materials.

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Thu Jan 01 00:00:00 UTC 1998