López García, Javier

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https://academica-e.unavarra.es/handle/2454/49434

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López García

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Javier

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Física

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750421

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811110

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2019 - 20202
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Author: López García, Javier × Subject: Metamagnetic shape memory alloys ×

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    PublicationOpen Access
    Influence of structural defects on the properties of metamagnetic shape memory alloys
    (MDPI, 2020) Pérez de Landazábal Berganzo, José Ignacio; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Lambri, Osvaldo Agustín; López García, Javier; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
    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.
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    PublicationOpen Access
    Influence of microstructure in the martensitic transformation and in the physical and magnetic properties in metamagnetic shape memory alloys
    (2019) López García, Javier; Recarte Callado, Vicente; Rodríguez Velamazán, José Alberto; Ciencias; Zientziak
    In this work we have focused in the study of the influence of the microstructure in metamagnetic shape memory alloys (Ni-Mn-In and Ni-Mn-Sn systems) together with the effect of Co-doping, in order to gain insight into these effects and to control and improve the properties of these materials. Starting with the ternary Ni-Mn-Sn system, we have stablished the correlation between microstructural parameters and magnetostructural properties in these alloys. We have characterized the different microstructural states induced by thermo-mechanical treatments and correlated them with the properties of the alloys. The cobalt-doped quaternary system, Ni-Co-Mn-Sn-Co has been the next subject of study. With the aim of obtaining further understanding of the effect of Cobalt doping the magnetic coupling, we have selected the Ni-Mn-In system as case study. Since in the systematic study of the effect of milling we have observed that long milling times lead to amorphous states, we have extended our study to the recrystallization processes in Ni-Co-Mn-Sn and Ni-Co-Mn-In alloys, with the analysis of the evolution of the different phases, the cell parameters and microstrutural parameters as grain size, micro and macrostrains.