Dynamic elastic properties and magnetic susceptibility across the austenite-martensite transformation in site-disordered ferromagnetic Ni-Fe-Al alloy

TL;DR

This study investigates the elastic and magnetic properties during the austenite-martensite transformation in a disordered Ni-Fe-Al alloy, revealing irreversible changes and phase memory effects during thermal cycling.

Contribution

It provides new experimental evidence of thermal hysteresis and phase memory effects in the thermoelastic martensitic transformation of a disordered Ni-Fe-Al alloy.

Findings

Irreversible thermoelastic changes occur in the austenite phase.

The system retains memory of martensitic growth during heating.

Experimental evidence of thermal hysteresis in the transformation.

Abstract

Besides permitting an accurate determination of the ferromagnetic-to-paramagnetic phase transition temperature and the characteristic temperatures for the beginning and end of the growth of martensite (austenite) phase at the expense of austenite (martensite) phase while cooling (heating), the results of an extensive ac susceptibility, sound velocity and internal friction investigation of the thermoelastic martensitic transformation in melt-quenched (site-disordered) Ni55Fe20Al25 alloy provide a clear experimental evidence for the following. Irreversible thermoelastic changes (thermal hysteresis) occur in the austenite phase in the premartensitic regime. In the heating cycle, the system retains the "memory" of the initiation and subsequent growth of the martensitic phase (at the expense of the parent austenite phase) that had taken place during the cooling cycle in the austenite-martensite phase coexistence region. We report and discuss these novel findings in this communication.