DSpace Repository :: Browsing by Author "Recarte Callado, Vicente"

Browsing by Author "Recarte Callado, Vicente"

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Open Access
119Sn Mössbauer spectroscopy for assessing the local stress and defect state towards the tuning of Ni-Mn-Sn alloys
(AIP Publishing, 2017) Unzueta, Iraultza; López García, Javier; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física
The influence of defects and local stresses on the magnetic properties and martensitic transformation in Ni50Mn35Sn15 is studied at macroscopic and atomic scale levels. We show that both the structural and magnetic properties of the alloy are very sensitive to slight microstructural distortions. Even though no atomic disorder is induced by milling, the antiphase boundaries linked to dislocations promote the antiferromagnetic coupling of Mn, resulting in a significant decrease in the saturation magnetization. On the other hand, the temperature range of the transformation is considerably affected by the mechanically induced local stresses, which in turn does not affect the equilibrium temperature between the austenitic and martensitic phases. Finally, we demonstrate that the recovery of the martensitic transformation is directly related to the intensity of the non-magnetic component revealed by 119Sn Mössbauer spectroscopy. This result opens the possibility of quantifying the whole contribution of defects and the local stresses on the martensitic transformation in Ni-Mn-Sn alloys.
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
Changes in the crystalline degree in neutron irradiated EPDM viewed through infrared spectroscopy and inelastic neutron scattering
(Rede Latino-Americana de Materiais, 2018) Lambri, Osvaldo Agustín; Giordano, E. D.; Bonifacich, Federico Guillermo; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Física; Fisika; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The changes in the degree of crystallinity in commercial Ethylene Propylene Diene rubber-type M (EPDM) irradiated with neutrons at different doses has been studied by means of inelastic neutron scattering and infrared absorption spectroscopy experiments. EPDM samples were taken from the housing of non-ceramic electrical insulators which are used in outdoor transmission lines of 66 kV. Inelastic neutron scattering spectra were recorded at 5 K with an accessible energy-transfer range between 180 - 3500 cm-1. Infrared studies were performed at room temperature with an energy transfer between 4000 - 400 cm-1. Controlled neutron irradiation allows to obtain different volume fraction and size of crystalline zones in EPDM. The obtained results are discussed and correlated with studies of differential scanning calorimetry, dynamic mechanical analysis and positron annihilation lifetime spectroscopy from where the changes in crystallinity in EPDM were indirectly studied. Inelastic neutron scattering studies were not appropriate for determining the changes in the crystallinity degree in neutron irradiated commercial EPDM. In contrast, from infrared absorption spectroscopy the changes in crystallinity could be determined successfully.
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
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
Entropy change caused by martensitic transformations of ferromagnetic shape memory alloys
(MDPI, 2017) L'vov, Victor A.; Cesari, Eduard; Kosogor, Anna; Torrens Serra, Joan; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Física; Fisika
In this paper, our most recent findings on the influence of magnetic order on the main transformational caloric and elastic properties of shape memory alloys (SMAs) are reviewed. It is argued that ferromagnetic order has a strong influence on the temperature interval of martensitic transformation (MT), the characteristics of stress-induced MT, and the shear elastic modulus of SMA. The problem of separation of the magnetic contributions to the entropy change ΔS and heat Q exchanged in the course of martensitic transformation (MT) of SMA is considered in general terms, and theoretical formulas enabling the solution of the problem are presented. As an example, the ΔS and Q values, which were experimentally determined for Ni-Mn-Ga and Ni-Fe-Ga alloys with different Curie temperatures TC and MT temperatures TM, are theoretically analyzed. It is shown that for Ni-Mn-Ga martensites with TM < TC, the ratio of elastic and magnetic contributions to the entropy change may be greater or smaller than unity, depending on the temperature difference TC – TM.
Open Access
Estudio de la modificación de la microestructura mediante tratamientos mecánicos y térmicos en una aleación ferromagnética de Ni-Mn-Ga. Correlación con la evolución de sus propiedades funcionales
(2013) Anaut Ezquer, Borja; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Física; Fisika
El presente trabajo se va a centrar en el estudio de la influencia de la molienda mecánica sobre las propiedades magnéticas y la transformación martensítica de una aleación ferromagnética en base Ni-Mn-Ga. La aplicación de la molienda mecánica permite introducir una gran concentración de defectos, deformaciones y tensiones internas en la microestructura de la aleación. La transformación martensítica es una transición sólido-sólido donde el grado de orden estructural y la densidad de defectos juegan un papel primordial en el balance energético entre ambas fases. Así, el proyecto presenta interés tanto desde un punto de vista básico como aplicado. Por una parte estudiar la influencia de los defectos inducidos en las propiedades funcionales de la aleación, y desde un punto de vista aplicado explorar la viabilidad de la molienda mecánica como método de obtención de partículas de tamaño micrométrico que presenten transformación martensítica. El gran problema de las aleaciones de Ni-Mn-Ga es su fragilidad. Una vía de optimización de las propiedades mecánicas es la reducción del tamaño de grano. Así la molienda mecánica podría ser un primer paso para la obtención de policristales de grano fino mediante una posterior compactación. En base a todo lo anterior, los objetivos de este Proyecto Fin de Carrera son la elaboración y estudio de las aleaciones con memoria de forma ferromagnéticas en el sistema Ni-Mn-Ga. En particular, se va a estudiar el efecto de la deformación mediante molienda mecánica en la transformación martensítica y en las propiedades magnéticas de dos aleaciones con composición atómica Ni50Mn28Ga22 y Ni50Mn27Ga23.
Open Access
Estudio de los procesos de ordenamiento en las aleaciones con memoria de forma de Ni50-Mn34-In16. Análisis de su influencia en las transformaciones magnéticas y estructurales y determinación de las energías de activación
(2012) Donázar Pérez, Patricia; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Física; Fisika
Con este proyecto fin de carrera se pretende estudiar mediante tratamientos térmicos de templado a distintas temperaturas cómo afectan a la temperatura de transformación martensítica, la temperatura de Curie y a la anchura de la región de transformación. Además, se estudiará el proceso de ordenamiento atómico que sufre la aleación mediante tratamientos isotérmicos en función del tiempo de envejecimiento. De esta forma y obteniendo sus correspondientes gráficas de evolución, se procederá a la caracterización de las cinéticas de ordenamiento y por último se determinarán las energías de activación. Para ello, se parte de estudios ya tabulados sobre el comportamiento de la aleación Ni50Mn34In16. Como por ejemplo, de la composición porcentual elegida Ni50Mn34In16 se conoce aproximadamente la ubicación de la temperatura de la transformación martensítica con respecto a la temperatura de Curie. Además de la relación estrecha entre el grado de orden atómico y la temperatura de templado. Estas características entre otras, son el punto de partida, pero en este proyecto además de contrastar resultados, se va a añadir el cálculo de las energías de activación como novedad.
Open Access
Evolution of magnetic response as a function of annealing temperature in Fe-based alloys
(Rede Latino-Americana de Materiais, 2018) Gargicevich, Damián; Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The magnetic response, coercive force and magnetic induction, in Fe-10at.% Si, Fe-6at.% Al-9at.% Si and Fe-4at.% Al-8at.% Ge alloys as a function of the annealing temperature was determined and correlated to the microstructural state. The microstructural characterization was made through differential thermal analysis, mechanical spectroscopy and neutron thermodiffraction studies. It has been determined that the increase in the order degree and the decrease in the mobility of structural defects lead to a deterioration of the magnetic quality of the alloys above detailed.
Open Access
Experimental observation of vacancy-assisted martensitic transformation shift in Ni-Fe-Ga alloys
(American Physical Society, 2019) Unzueta, Iraultza; Alonso de Robador Lorente, Daniel; Cesari, Eduard; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; García, José Ángel; Plazaola, Fernando; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Positron annihilation lifetime spectroscopy is used to experimentally demonstrate the direct relationship between vacancies and the shift of the martensitic transformation temperature in a Ni55Fel7Ga28 alloy. The evolution of vacancies assisting the ordering enables shifts of the martensitic transformation up to 50 K. Our results confirm the role that both vacancy concentration and different vacancy dynamics play in samples quenched from the L2(1) and B2 phases, which dictate the martensitic transformation temperature and its subsequent evolution. Finally, by electron-positron density functional calculations V-Ni is identified as the most probable vacancy present in Ni55Fe17Ga28. This work evidences the capability of vacancies for the fine-tuning of the martensitic transformation temperature, paving the way for defect engineering of multifunctional properties.
Open Access
Giant direct and inverse magnetocaloric effect linked to the same forward martensitic transformation
(Springer Nature, 2017) Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Beato López, Juan Jesús; Rodríguez Velamazán, José Alberto; Sánchez Marcos, J.; Gómez Polo, Cristina; Cesari, Eduard; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física
Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic transformation (martensite to austenite). In some of these alloys, the austenite phase can be retained on cooling under high magnetic fields, being the retained phase metastable after field removing. Here, we report a giant direct magnetocaloric effect linked to the anomalous forward martensitic transformation (austenite to martensite) that the retained austenite undergoes on heating. Under moderate fields of 10 kOe, an estimated adiabatic temperature change of 9 K has been obtained, which is (in absolute value) almost twice that obtained in the conventional transformation under higher applied fields. The observation of a different sign on the temperature change associated to the same austenite to martensite transformation depending on whether it occurs on heating (retained) or on cooling is attributed to the predominance of the magnetic or the vibrational entropy terms, respectively.
Open Access
High functional 3D printed PCL/FSMA magnetic composites
(IOP Publishing, 2024) Lambri, Fernando Daniel; Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Khanna, Deepali; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Lambri, Melania Lucila; Zelada, Griselda Irene; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The capacity of adaptability of a three-dimensional-printed composite of polycaprolactone-based containing micro-particles of ferromagnetic shape memory alloy of composition Ni45Mn36.7In13.3Co5 was determined. Composites exhibit an increase in both damping and modulus values up to around 11%, at temperatures close to 325 K, when applying a magnetic field of 120 kA m−1. In addition, composites show also an increase in the damping values of around 50% at temperatures near 333 K, related to the martensitic transformation, which is promoted by an increase in the oscillating strain from 0.5 × 10−4 up to 2 × 10−4 and when applying a magnetic field of 120 kA m−1. Moreover, the maximum temperature of use of the composite can be increased by means of a magnetic field. These adaptability qualities make this functional composite attractive, for the vibration control at elevated temperatures as well as the potential applications in magnetocaloric devices.
Open Access
Identification of a Ni-vacancy defect in Ni-Mn-Z (Z = Ga, Sn, In): an experimental and DFT positron-annihilation study
(American Physical Society, 2019) Unzueta, Iraultza; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Zabala, Nerea; García, José Ángel; Plazaola, Fernando; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
By means of experimental positron-annihilation-lifetime measurements and theoretical density functional theory (DFT) positron-lifetime calculations, vacancy-type defects in Ni50Mn50−xSnx (x = 25, 20, 15, 13, 10) and Ni50Mn50−xInx (x = 25, 20, 16, 13) systems are systematically studied. The study is extended to Ni-Mn-Ga systems as well. Experimental results are complemented with electron-positron DFT calculations carried out within the local density approximation and generalized gradient approximation, where five different parametrizations accounting for the γ (r) enhancement factor are analyzed. Theoretical results indicate that the Boronski-Nieminen parametrization of γ (r) is the one that best predicts the experimental results, which ultimately enables us to identify VNi as the vacancy present in the studied samples. The characteristic positron lifetime related to VNi ranges between 181 and 191 ps in Ni-Mn-Sn/In systems. Positron-annihilation-lifetime spectroscopy results in these two systems delimit the lower bound of the achievable vacancy concentration, which is much larger compared with the reported values in Ni-Mn-Ga systems. The present work, along with setting the basis for positron simulations in Ni-Mn based Heusler alloys, delimits the effect that the variation of vacancies has in the martensitic transformation in Ni-Mn-Sn systems.
Open Access
Influence of defects on the irreversible phase transition in the Fe-Pd doped with Co and Mn
(Rede Latino-Americana de Materiais, 2018) Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The appearance of BCT martensite in Fe-Pd-based ferromagnetic shape memory alloys, which develops at lower temperatures than the thermoelastic martensitic transition, deteriorates the shape memory properties. In a previous work performed in Fe70Pd30, it was shown that a reduction in defects density reduces the non thermoelastic FCT-BCT transformation temperature. In the present work, the influence of quenched-in-defects upon the intensity and temperature of the thermoelastic martensitic (FCC-FCT) and the non thermoelastic (FCT-BCT) transitions in Fe-Pd doped with Co and Mn is studied. Differential scanning calorimetric and mechanical spectroscopy studies demonstrate that a reduction in the dislocation density the stability range of the FCC-FCT reversible transformation in Fe67Pd30Co3 and Fe66.8Pd30.7Mn2.5 ferromagnetic shape memory alloys.
Open 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.
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
Influencia de la adición de Ti en la transformación martensítica y las propiedades magneto-mecánicas de la aleación metamagnética con memoria de forma Ni-Mn-In
(2012) Urdiáin Goñi, Adrián; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Física; Fisika
Los objetivos básicos de este Proyecto Fin de Carrera son: elaborar cuatro muestras, ya que no son comerciales: Ni50Mn34In16-xTix(x= 0, 0.5, 1, 2); determinar las propiedades de la transformación martensítica en cada una de las muestras caracterizadas; realizar un estudio microestructural, (tamaño de grano, posibles precipitados de titanio en cada una de las muestras, etc...); analizar las propiedades magnéticas y estudiar su evolución frente al porcentaje de titanio de cada muestra; analizar y estudiar la microdureza del material en función del porcentaje de titanio; y realizar un estudio de las propiedades mecánicas de cada muestra elaborada.
Open Access
Influencia de tratamientos isotérmicos en las propiedades de la transformación martensítica en aleaciones con memoria de forma Ni-Fe-Ga
(2013) Lorea Larrea, Iosu; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Física; Fisika
En este proyecto se ha estudiado la influencia de los tratamientos térmicos en las propiedades de la transformación martensítica de una aleación con memoria de forma en base Ni-Fe-Ga. En concreto se ha analizado la evolución de la transformación martensítica durante tratamientos isotermos de envejecimiento post-templado con el fin de determinar la estabilidad térmica de la transformación y estimar las energías de activación de los procesos térmicamente activados.
Open Access
Influencia de tratamientos térmicos de temple en las propiedades de la transformación martensítica en aleaciones con memoria de forma Ni-Fe-Ga
(2013) Alonso de Robador Lorente, Daniel; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación; Telekomunikazio eta Industria Ingeniarien Goi Mailako Eskola Teknikoa; Física; Fisika
Este proyecto se va a centrar en el estudio de la aleación con memoria de forma ferromagnética Ni-Fe-Ga, en concreto en la influencia de los tratamientos térmicos de temple y envejecimiento post-temple en las propiedades de la transformación martensítica de una aleación Ni54.4-Fe18.6-Ga27 con Tm en torno a temperatura ambiente. Los objetivos de este proyecto son los siguientes: 1. Caracterización: Caracterización microestructural de la aleación ; Estudio de la composición y presencia de precipitados con los tratamientos térmicos. 2. Estudio de la influencia de los tratamientos térmicos de temple: Tratamiento térmico de temple; Tratamiento térmico de envejecimiento post-temple. 3. Análisis de las cinéticas de ordenamiento: Método Kissinger para el estudio de cinéticas de calentamiento y determinación de las energías de activación.
Open Access
Long-range atomic order and entropy change at the martensitic transformation in a Ni-Mn-In-Co metamagnetic shape memory alloy
(MDPI, 2014) Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Cesari, Eduard; Rodríguez Velamazán, José Alberto; Física; Fisika
The influence of the atomic order on the martensitic transformation entropy change has been studied in a Ni-Mn-In-Co metamagnetic shape memory alloy through the evolution of the transformation temperatures under high-temperature quenching and post-quench annealing thermal treatments. It is confirmed that the entropy change evolves as a consequence of the variations on the degree of L21 atomic order brought by thermal treatments, though, contrary to what occurs in ternary Ni-Mn-In, post-quench aging appears to be the most effective way to modify the transformation entropy in Ni-Mn-In-Co. It is also shown that any entropy change value between around 40 and 5 J/kgK can be achieved in a controllable way for a single alloy under the appropriate aging treatment, thus bringing out the possibility of properly tune the magnetocaloric effect.