Given its quantum mechanical origin, magnetostriction itself is atomically fast. This ultimate speed is affected by packaging it into a useful solid rod of terfenol-d.

The rod converts an input magnetic field into a mechanical output. The time rate of change of that mechanical output, its speed, requires a time rate of change of the magnetic field. This in turn depends on the time rate of change of current through the actuator coil.

• The maximum time rate of change of voltage to effect a change in current is determined by the materials and construction of the solenoid coil and by power supply capabilities.
  
  
  • A design can be optimized for speed by, for instance, trading coil turns for current.

Magnetic field changes diffuse into and out of the alloy rod at a speed fixed by its geometry and material constants. Local mechanical changes occur in response to local magnetic field changes.

• Known countermeasures to this delay enable effective ultrasonic actuators.

The speed of an elastic plane wave propagating along the axis of an alloy rod is not less than 1,600 meters per second.