Resonant ultrasound spectroscopy – a tool to probe magneto-elastic properties of ferromagnetic shape memory alloys

摘要

Resonant ultrasound spectroscopy (RUS) was used to investigate the changes of elastic properties induced by magnetic field in magnetic shape memory alloys Ni-Mn-Ga and Co-Ni-Al. In contrast to large magneto-elastic response of Ni2MnGa austenite, there is only very weak response of Co-Ni-Al. This indicates that the austenite phase of Ni-Mn-Ga can have a privileged position and this may be a reason for the existence of magnetic shape memory effect. In contrast to austenite, the magneto-elastic response in Ni-Mn-Ga martensite is very small with large damping due to existence of twin boundaries. The measurement showed that RUS can be a powerful method to probe magneto-elastic properties of shape memory alloys.