Thermo-magnetic characterization of phase transitions in a Ni-Mn-In metamagnetic shape memory alloy

Ultraslow calorimetric studies of the martensitic transformation of NiFeGa alloys: detection and analysis of avalanche phenomena

“…The jerks or avalanches characterize, at the macroscopic scale, the energies associated with the intermittent dynamic of the phase transition as shown by acoustic emission measurements [26], calorimetry [34,45] and by high precision calorimetry [18,21,32,33]. They are best analyzed in the adiabatic limit, when thermal driving is slow enough to prevent overlapping.…”

“…Low temperature martensitic transformations are characterized by a very fast diffusionless growth that can be detected by magnetic measurements [17,18], thermal measurements [19][20][21], XRD-in situ techniques [22], and electrochemical impedance [23]. The diffusionless growth can be described as an autocatalytic kinetic process (e.g.…”

“…The detection of avalanches has traditionally required the use of experimental techniques sensitive to the strain jumps that occur during relaxation such as acoustic emission [27]; magnetic Barkhausen emission have also provided results in this field [29][30][31]. Alternatively, calorimetric techniques have proven able to detect and measure the energy associated with the avalanches, which are observed as spikes in DTA traces of high resolution conduction calorimetry [18,21,32,33] and in differen-tial scanning calorimetry (DSC) traces [34][35][36]. These techniques provide a straightforward identification of the characteristic energies involved in the jerky events at the prize of more challenging experimental conditions.…”