Further increase in field makes the material to acts as a single domain as all magnetic moments rotate coherently from the easy axis into the direction of the field. This produces saturation of the magnetization. Typical magnetization and strain loops [shown in Figure 29.2(a) and (b)] illustrate the burst region and saturation effects. From a design perspective, magnetic biasing is used to centre operation in the burst region for optimum performance.

Figure 29.2 (a) Experimental magnetic induction and (b) Total strain with change in magnetic field

For low magnetic field levels, partial excursions in the M −H or ε − H curve are approximately linear. The hysteresis can be attributed to the irreversible impediment to domain motion by pinning sites, such as when domain walls move across twin boundaries in Terfenol-D.

One advantage of magnetostrictive transducer over other types of transducers is that they can be driven with conventional low impedance amplifiers suggesting that magnetostrictive transducer may work at low driving voltages. This is useful in many applications and can greatly simplify the amplifier design.