Influence of Structural Defects on the Properties of Metamagnetic Shape Memory Alloys

J I Pérez-Landazábal,V Sánchez-Alarcos,M Jimenez Ruiz,J.A Rodríguez-Velamazán,V Recarte,J López-García,J.A García,F Plazaola,D L.R Khanna,F G Bonifacich,I Unzueta,O A Lambri,E Cesari

doi:10.3390/met10091131

Abstract

The production of μ-particles of Metamagnetic Shape Memory Alloys by crushing and subsequent ball milling process has been analyzed. The high energy involved in the milling process induces large internal stresses and high density of defects with a strong influence on the martensitic transformation; the interphase creation and its movement during the martensitic transformation produces frictional contributions to the entropy change (exothermic process) both during forward and reverse transformation. The frictional contribution increases with the milling time as a consequence of the interaction between defects and interphases. The influence of the frictional terms on the magnetocaloric effect has been evidenced. Besides, the presence of antiphase boundaries linked to superdislocations helps to understand the spin-glass behavior at low temperatures in martensite. Finally, the particles in the deformed state were introduced in a photosensitive polymer. The mechanical damping associated to the Martensitic Transformation (MT) of the particles is clearly distinguished in the produced composite, which could be interesting for the development of magnetically-tunable mechanical dampers.

Highlights

The change in the interatomic distances caused by the occurrence of a thermoelastic MartensiticTransformation (MT) in Metamagnetic Shape Memory Alloys (MSMA) results in large magnetization changes (∆M) at the transformation temperature [1,2,3,4]
Ni45 Co5 Mn36 In14 Metamagnetic alloys were synthetized from high purity elements by arc-melting under protective argon atmosphere
The alloys were milled in an agate mortar until reaching a uniform particle-size distribution

Summary

Introduction

The change in the interatomic distances caused by the occurrence of a thermoelastic Martensitic. Transformation (MT) in Metamagnetic Shape Memory Alloys (MSMA) results in large magnetization changes (∆M) at the transformation temperature [1,2,3,4]. The strong dependence of the magnetic exchange interactions on the Mn-Mn distances [5,6,7] is responsible for such a change and allows the induction of the MT by external magnetic fields. The inherent damping properties of shape memory alloys can be used for active noise reduction and mechanical damping applications [15,16]. The compositional [17,18,19,20]

Methods

Results

Conclusion