• Sanchez Llamazares, Jose Luis

Abstract

<jats:p>The characteristics of magnetostructural coupling play a crucial role in the magnetic field-driven behaviour of magnetofunctional alloys. The availability of magnetostructural coupling over a broad temperature range is of great significance for scientific and technological purposes. This work demonstrates that strong magnetostrucural coupling can be achieved over a wide temperature range (222 to 355 K) in Co-doped high Mn-content Mn<jats:sub>50</jats:sub>Ni<jats:sub>42−<jats:italic>x</jats:italic></jats:sub>Co<jats:sub><jats:italic>x</jats:italic></jats:sub>Sn<jats:sub>8</jats:sub> (0 ≤ <jats:italic>x</jats:italic> ≤ 10) melt-spun ribbons. It is shown that, over a wide composition range with Co content from 3 to 9 at.%, the paramagnetic austenite first transforms into ferromagnetic austenite at <jats:italic>T</jats:italic><jats:sub>C</jats:sub> on cooling, then the ferromagnetic austenite further transforms into a weakly magnetic martensite at <jats:italic>T</jats:italic><jats:sub>M</jats:sub>. Such strong magnetostructural coupling enables the ribbons to exhibit field-induced inverse martensitic transformation behaviour and a large magnetocaloric effect. Under a field change of 5 T, a maximum magnetic entropy change Δ<jats:italic>S</jats:italic><jats:sub>M</jats:sub> of 18.6 J kg<jats:sup>−1</jats:sup> K<jats:sup>−1</jats:sup> and an effective refrigerant capacity <jats:italic>RC</jats:italic><jats:sub>eff</jats:sub> of up to 178 J kg<jats:sup>−1</jats:sup> can be achieved, which are comparable with or even superior to those of Ni-rich Ni–Mn-based polycrystalline bulk alloys. The combination of high performance and low cost makes Mn–Ni–Co–Sn ribbons of great interest as potential candidates for magnetic refrigeration.</jats:p>

Topics

• impedance spectroscopy
• melt
• phase transition