Ni-Mn-Sn-Cu Alloys after Thermal Cycling: Thermal and Magnetic Response.

Asma Wederni,Joan-Josep Suñol,Julián-María González,Mihail Ipatov,Mohamed Khitouni

doi:10.3390/ma14226851

Asma Wederni, Joan-Josep Suñol + Show 3 more

Open Access

https://doi.org/10.3390/ma14226851

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Abstract

Heusler Ni-Mn-Sn-based alloys are good candidates for magnetic refrigeration. This application is based on cycling processes. In this work, thermal cycles (100) have been performed in three ribbons produced by melt-spinning to check the thermal stability and the magnetic response. After cycling, the temperatures were slowly shifted and the thermodynamic properties were reduced, the entropy changed at about 3–5%. Likewise, the thermomagnetic response remains similar. Thus, these candidates maintain enough thermal stability and magnetic response after cycling. Likewise, Cu addition shifts the structural transformation to higher temperatures, whereas the Curie temperature is always near 310 K. Regarding magnetic shape memory applications, the best candidate is the Ni49Mn36 Sn14Cu1 alloy.

Highlights

Ni-Mn-Sn-based Heusler ferromagnetic alloys are multifunctional materials due to the coupling of a reversible solid-state first order transformation and a second order magnetic transformation
Addition of small quantities of a fourth element in the ternary off-stoichiometry Heusler alloys has been proposed as a way to improve the functional response and to tailor the transition temperatures [7]
This trend opens the possibility of deliberate changes in the transition temperatures and benefits while forcing phase transitions by a temperature and magnetic field [9]

Summary

Introduction

Ni-Mn-Sn-based Heusler ferromagnetic alloys are multifunctional materials due to the coupling of a reversible solid-state first order transformation (austenite to martensite) and a second order magnetic transformation (ferromagnetic to paramagnetic). In these alloys, the transformations can be induced by mechanical stress, temperature and/or external magnetic field. A minor amount of other metallic elements, such as Zn [14], Al [15] or Pd [16], or metalloids, such as B [17] have been checked In these compounds, the main effect is the shift of the transition temperatures. The main objective is to analyze the thermal and magnetic response to check its thermal and magnetic stability after cycling

Materials and Methods

Crystallographic Analysis

Magnetic Analysis