Person: La Roca, Paulo Matías
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La Roca
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Paulo Matías
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Ciencias
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0000-0003-0856-6052
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812003
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Publication Embargo Monitoring structural transformations in metamagnetic shape memory alloys by non-contact GMI technology(IOP Publishing, 2023) Beato López, Juan Jesús; La Roca, Paulo Matías; Algueta-Miguel, Jose M.; Garayo Urabayen, Eneko; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC; Zientziak; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio IngeniaritzarenDifferent applications based on metamagnetic shape memory alloy (MSMA) require monitoring the evolution of the martensitic transformation (MT) to optimize the actuation mechanism. To avoid interaction with the active material, a non-contact technique would be ideal. Nevertheless, non-contact detection involves complex methods like diffraction, optical analysis, or electromagnetic technology. The present work demonstrates that the MT can be monitored without interaction with the active material using a low-cost technology based on the Giant Magnetoimpedance (GMI) effect. The GMI sensor is based on a (CoFe)SiB soft magnetic wire submitted to an alternating current and whose second harmonic voltage variation allows to detect changes in the strength of the stray magnetic fields linked to the metamagnetic phase transition. The sensor has been tested using the MT of a NiMnInCo MSMA. A specific application for environmental temperature control using the non-contact GMI sensor is proposed.Publication Open Access Strategies to increase austenite FCC relative phase stability in high-Mn steels(Elsevier, 2021) Guerrero, L.M.; La Roca, Paulo Matías; Malamud, M.F.; Butera, A.; Baruj, A.; Sade, M.; Institute for Advanced Materials and Mathematics - INAMAT2Several strategies to increase the FCC austenite stability compared to BCC and HCP martensites have been tested and are discussed. The relative stability of the different phases was analyzed by studying the effects of: a) grain size, b) antiferromagnetic ordering of the austenite, c) thermal cycling through the FCC-HCP transition, d) plastic deformation of the austenite and e) combined effects. As a first step, the effect of decreasing the grain size was analyzed in Fe-Mn alloys for Mn contents smaller than 18 wt.%, where BCC and HCP martensites compete in stability. Formation of the BCC phase is inhibited for 15 wt.% and 17 wt.% of Mn for grain sizes smaller than 2 μm. This enabled, for the first time at these compositions, the measurement of the Neel temperature of the austenite using specific heat and magnetic measurements. A comparison of the obtained transition temperatures with accepted models is discussed. The effect of modifying the grain size on the FCC-HCP transition temperatures was also analyzed for 15 wt.% and 17 wt.% Mn contents showing a complete HCP inhibition for grain sizes smaller than 200 nm. A nucleation model for the HCP martensite is considered which includes an additional resistance to the transformation term depending on the austenitic grain size. Additional combined effects on the FCC stabilization are discussed like the interaction between the antiferromagnetic ordering and the introduction of defects by thermal cycling through the martensitic transformation. The analysis can be easily applied to systems with a larger number of components. Results obtained in the Fe-Mn-Cr system are also presented.Publication 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 AMELECThe 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.Publication Open Access Martensitic transformation controlled by electromagnetic field: from experimental evidence to wireless actuator applications(Elsevier, 2022) Garayo Urabayen, Eneko; La Roca, Paulo Matías; Gómez Polo, Cristina; 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 GobernuaMechanical actuators based on shape memory alloys (SMA) are becoming a key component in the development of novel soft robotic applications and surgically implantable devices. Their working principle relies in the temperature induced martensitic transformation (MT), which is responsible of the actuation mechanism. In this work, we found experimental evidence to show that the martensitic transformation can be controlled by electromagnetic field (EF) by a wireless process in ferromagnetic shape memory alloys. It is shown that the martensitic transformation can be driven by an external EF (frequency 45 kHz) while the specific absorption rate (SAR), which was determined through real-time dynamic magnetization measurements, allows the instantaneous monitoring of the transformation evolution. On the basis of the obtained results, we propose a strategy to achieve a battery-free wireless SMA actuator that can be remotely controlled. This concept can be applicable to other SMA material that exhibit a similar magneto-structural phase transitionPublication Open Access Designing a wider superelastic window(American Association for the Advancement of Science, 2020) La Roca, Paulo Matías; Sade, M.; Ciencias; ZientziakAdding chromium to an iron alloy enables shape recovery over a wide temperature rangePublication Open Access Magnetically activated 3D printable polylactic acid/polycaprolactone/magnetite composites for magnetic induction heating generation(Springer, 2023) Galarreta Rodríguez, Itziar; López Ortega, Alberto; Garayo Urabayen, Eneko; Beato López, Juan Jesús; La Roca, Paulo Matías; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Gómez Polo, Cristina; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate PublikoaAdditive manufacturing technology has attracted the attention of industrial and technological sectors due to the versatility of the design and the easy manufacture of structural and functional elements based on composite materials. The embedding of magnetic nanoparticles in the polymeric matrix enables the development of an easy manufacturing process of low-cost magnetically active novel polymeric composites. In this work, we report a series of magnetic composites prepared by solution casting method combining 5 to 60 wt.% of 140 ± 50 nm commercial Fe3O4 nanoparticles, with a semi-crystalline, biocompatible, and biodegradable polymeric blend made of polylactic acid (PLA) and polycaprolactone (PCL). The composites were extruded, obtaining 1.5 ± 0.2 mm diameter continuous and flexible filaments for fused deposition modelling 3D printing. The chemical, magnetic, and calorimetric properties of the obtained filaments were investigated by differential scanning calorimetry, thermogravimetric analysis, magnetometry, and scanning electron microscopy. Furthermore, taking advantage of the magnetic character of the filaments, their capability to generate heat under the application of low-frequency alternating magnetic fields (magnetic induction heating) was analyzed. The obtained results expose the versatility of these easy manufacturing and low-cost filaments, where selecting a desired composition, the heating capacity can be properly adjusted for those applications where magnetic induction plays a key role (i.e., magnetic hyperthermia, drug release, heterogeneous catalysis, water electrolysis, gas capture, or materials synthesis).Publication Open Access A short review on the effect of Cr on the fcc-hcp phase transition in Fe-Mn-based alloys(Springer, 2020) Guerrero, L.M.; La Roca, Paulo Matías; Malamud, M.F.; Baruj, A.; Sade, M.; Ciencias; ZientziakThe effect of Cr on the fcc–hcp martensitic transformation in the Fe–Mn–Cr system has been discussed considering different aspects: (a) the relative phase stabilities, (b) the magnetic order of the fcc phase, (c) the structural parameters and volume change between fcc and hcp, (d) the driving force of the martensitic transformation and relevant thermodynamics quantities, (e) the thermal cycling behavior, and (f) the pseudoelastic effect. Particularly, in this work it has been found that when Cr content increases, the effect of cycling on the energy barrier decreases. This may be explained by a small volume change, which could lead to a slighter introduction of plastic deformation during thermal cycling through the martensitic transition.Publication Embargo Room temperature huge magnetocaloric properties in low hysteresis ordered Cu-doped Ni-Mn-In-Co alloys(Elsevier, 2022) La Roca, Paulo Matías; López García, Javier; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Rodríguez-Velamazán, José Alberto; Pérez de Landazábal Berganzo, José Ignacio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Gobierno de Navarra / Nafarroako Gobernua, PC017–018 AMELECThe reduction of the thermal hysteresis in first order magnetostructural transition is a determining factor to decrease energy losses and to improve the efficiency of magnetocaloric cooling based systems. In this work, a Cu doped NiMnInCo metamagnetic shape memory alloy (MMSMA) exhibiting a narrow thermal hysteresis (around 5 K) at room temperature has been designed. In this alloy, the induced L21 ordering process affects the phase stability in an unusual way compared to that observed in NiMnInCo and other NiMn based alloys. This ordering produces an increase in the Curie temperature of the austenite but hardly affects the mar tensitic transformation temperatures. As a consequence, the ordering increases the magnetization of the austenite without changing the transformation temperatures, doubles the sensitivity of the transformation to magnetic fields (the Claussius-Clapeyron slope goes from 2.1 to 3.9 K/T), improves the magnetocaloric effect, the reversibility and finally, enhances the refrigeration capacity. In addition, the magnetic hysteresis losses are among the lowest reported in the literature and the effective cooling capacity coefficient RCeff reaches 86 J/Kg for 2 T (15 % higher than those found in Ni-Mn based alloys) and 314 J/Kg for 6 T fields. Therefore, the ordered alloy possesses an excellent combination of low thermal hysteresis and high RCeff, not achieved previously in metamagnetic shape memory alloys near room temperature.Publication Open Access Alternative thermal cycling treatment to produce abnormal grain growth in feMnAlNi alloys: study of composition variations and effects on the relative phase stabilities(Springer, 2021) La Roca, Paulo Matías; Guerrero, L.M.; Baruj, A.; Vallejos, J. M.; Sade, M.; Institute for Advanced Materials and Mathematics - INAMAT2An alternative method to obtain abnormal grain growth in Fe–Mn–Al–Ni system is presented. A crucible is used to control the cooling speed of the samples from 1200 °C enabling the nucleation of the equilibrium fcc phase. This fcc structure leads to an abnormal grain growth after heating to 1200 °C, temperature at which the bcc phase is stable. In this way, crystals with a mean diameter of 18 mm are obtained after 4 thermal cycles which take approximately 2 h. Additionally, precise composition measurements using neutron activation allowed the detection of a decrease in Mn content after each thermal cycle. Using electrical resistivity measurements, the effect of the variation of Mn content on the relative phase stability between the bcc austenite and the fcc martensite has been observed and is discussed here.