Open Access
Correlation between particle size and magnetic properties in soft-milled Ni45Co5Mn34In16 powders
(Elsevier, 2021) Khanna, Deepali; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PC017-018 AMELEC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The effect of microstructural defects induced by mechanical milling has been studied in a Ni–Mn–In–Co metamagnetic shape memory alloy. The martensitic transformation and Curie temperatures do not change with grinding, thus pointing out to a null variation of long range atomic order as a consequence of the deformation. Nevertheless, the enthalpy change of the martensitic transformation highly decreases. This, and the large thermal stabilization of the martensite (with shifts on the temperature of the first reverse martensitic transformation up to 60 K), indicate the presence of a huge amount of internal stresses and microstructural defects in the obtained micro-particles. The presence of such defects considerably affects the saturation magnetization in austenite whereas almost no effect is observed in martensite. The magnetocaloric effect has been evaluated in samples with three different particle sizes. In spite of the MCE value is lower than in the bulk, the broader temperature range for the martensitic transformation in the powders makes the relative cooling power be comparable to that in the bulk. The as-milled micro-particles can be then considered as good preliminary candidates for magnetic refrigeration applications at the microscale.
Open 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.
Open Access
Effect of high-energy ball-milling on the magnetostructural properties of a Ni45Co5Mn35Sn15 alloy
(Elsevier, 2021) López García, José Luis; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Rodríguez Velamazán, José Alberto; Unzueta, Iraultza; García, José Ángel; Plazaola, Fernando; La Roca, Paulo Matías; Pérez de Landazábal Berganzo, José Ignacio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PC017-018 AMELEC
The effect of high-energy ball-milling on the magnetostructural properties of a Ni45Co5Mn35Sn15 alloy in austenitic phase at room temperature has been analyzed by neutron and high-resolution X-ray diffraction. The ball milling promotes a mechanically-induced martensitic transformation as well as the appearance of amorphous-like non-transforming regions, following a double stage; for short milling times (below 30 min), a strong size reduction and martensite induction occur. On the opposite, for longer times, the increase of strains predominates and consequently a larger amount of non-transforming regions appears. The effect of the microstructural defects brought by milling (as dislocations) on both the enthalpy change at the martensitic transformation and the high field magnetization of the austenite has been quantitatively estimated and correlated to the internal strains. Contrary to what occurs in ternary Ni-Mn-Sn alloys, the mechanically-induced defects do not change the ferromagnetic coupling between Mn atoms, but just cause a net reduction on the magnetic moments.
Open Access
Analysis of the strain misfit between matrix and inclusions in a magnetically tunable composite
(Elsevier, 2021) Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Lambri, Fernando Daniel; Bozzano, P. B.; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
A magnetically tunable composite has been elaborated by embedding microparticles of a metamagnetic shape memory alloy on a photo curable resin. The strain misfit between the polymeric matrix and the inclusions has been analysed within Eshelby formalism. Results show the non-appearance of active microcracks at the interfaces where strains are induced by the martensitic transformation in the microparticles. Even though the martensitic transformation is well detected, the values of misfit β coefficient indicate that the matrix accommodates all the stresses induced by the inclusions. A stable surface interaction between particles and matrix is also confirmed during thermal cycles. It is also demonstrated that the damping capacity of the composites can be tuned by combining oscillating strain, fillers content and magnetic field. The proposed model could be applied to analyse the mechanical stability in polymer matrix composites in which fillers undergo a first order transition with volume change and associated deformation.
Open Access
Magnetically tunable damping in composites for 4D printing
(Elsevier, 2021) Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Composite materials are being used in the design of new devices to produce more functional, cheap and on-demand products. In particular, 3D printing technology based on composites opens a huge field enabling the freedom of design and the ability to manufacture complex structures. In this context, the analysis of the functional properties of printable composites is of great importance. The work is focused on the analysis of the mechanical damping of a composite made with different concentrations of a Ni45Mn36.7In13.3Co5 metamagnetic shape memory alloy into an UV-curing polymer. The composites provide a bulk material containing very brittle metallic μ-particles that can be handled for technological applications. Damping and dynamic modulus of the composites were modified with small magnetic fields below 100 kA/m, proving that the damping capacity can be tuned by applying an external magnetic field. From the measurements, it has been also possible to determine the intrinsic damping and moduli of the alloy particles, which show the characteristic properties linked to the MT. These preliminary results allow proposing this composite material as a potential functional material to be used in the design of printable devices for magneto-mechanical damping applications.