Comparison between the Rare Earth Magnetostrictive Material and Piezoelectric Ceramic

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Comparison between the Rare Earth Magnetostrictive Material and Piezoelectric Ceramic


The rare earth magnetostrictive material (short for GMM, that is Terfenol-D), a kind of alloy which is made from the rare earth metal terbium, dysprosium and iron, is a sort of new material for transducer. One meter long GMM stick can elongate 1-2 millimeter along the provided magnetic field, and this capacity is ten to hundred times of traditional piezoelectric ceramic. Meanwhile, this material is capable of actuating and sensor, featuring great PPM, high precision, instant response and efficient transduction etc. The magnetostrictive material and piezoelectric ceramic have been widely used in national military defense, electronics industry, mechanical industry and ultrasonic fields. Chiefly, it makes use of the efficient transducing of electromagnetism and mechanical energy. In this case, it can generate and improve series practical instruments, such as acoustics instruments, mechanics instruments (actuator and executor), electronics instruments (sensor, signal generator), electromagnetism (close executor, electric current controlled executor), transducer (ultrasonic transducer, sonic transducer) and so on.
    In recent years, with the constant development and exploitation, the trend of taking the place of piezoelectric ceramic has fixed, especially the efficiency of transducing is better than traditional piezoelectric ceramic material.

The strong point of the rare earth magnetostrictive material comparing with the traditional piezoelectric ceramic material

Giant PPM at the even temperature is over 0.15%
Curie temperature 380→―420→, and it can work at the 200→ high temperature zone freely.
It can generate force 300kgf/cm2 in a provided magnetic field of 80KAm-1(1K0e)
High transduction efficiency, coupling factor over 0.75
The low driving voltage, it can be driven by several voltage, but the piezoelectric ceramic needs thousands of volt.
Strong structure in the shape of stick, hardly can generate damaging affect.
Reasonably designed and easily control, with the mighty concept of digital piezoelectric ceramic is uneasily to control with the strong obscure conception.
Slow sound velocity, it can reduce mechanical resonance size using in ultrasonic instruments.
Can stand the high pressure of 200MPa, it is suitable to high pressure executor and giant power sonic transducer etc. But the piezoelectric ceramic can not bear it.
The instant response to the given force and magnetization the uncomparable advantage in the field of instant executor.
No fatigue and no aging which the piezoelectric ceramic material caused.
Suitable to working in the low frequency zone, it is better than any traditional material in the scale of 0-5KHz in the aspect of transduction.