Measurement of ferromagnetic phase transformation with Barkhausen type experiments

Classical Barkhausen effect measurements are used to determine rapid magnetization changes in small volume elements. Typically, one Barkhausen signal corresponds to a change in the magnetization orientation in the magnetic domain. Similarly, the rapid growth of a ferromagnetic phase from a nonferromagnetic matrix should lead to a Barkhausen type signal, since the signal in a pick up coil is a function only of the magnetization change with time. It was possible to follow the growth of ferromagnetic phases in TRIP steel with time resolutions of the order of 10^-5sec, with transformation in volumes of 10^-9cm³, if the volume transformation rate was of the order of 10^-3cm³/sec, or larger.