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Papers by Paloma Adeva

Metals, 2020

The corrosion behaviour of Mg98.5-Nd1-Zn0.5 (at. %) alloy was studied in phosphate buffered salin... more The corrosion behaviour of Mg98.5-Nd1-Zn0.5 (at. %) alloy was studied in phosphate buffered saline (PBS) solution to evaluate its degradation performance as a potential candidate for biomedical applications. The alloy, produced by casting and hot extrusion, consists of a fine-grained magnesium matrix with an average grain size of 3.8 μm embedding a high volume fraction of (Mg, Zn)12Nd precipitates. Hydrogen release tests revealed a stable low corrosion rate of 0.6 mm/year after 24 h of immersion. Electrochemical testing data proved good correlation with the data from hydrogen evolution, with the corrosion rate stabilizing below 1 mm/year.

Metals, 2019

The evolution of the microstructure and mechanical properties during equal channel angular pressi... more The evolution of the microstructure and mechanical properties during equal channel angular pressing processing has been studied in an extruded Mg-Gd-Y-Zn alloy containing long-period stacking ordered phases. After extrusion, the microstructure is characterized by the presence of long-period stacking ordered fibers elongated along the extrusion direction within the magnesium matrix. The grain structure is a mixture of randomly oriented dynamic recrystallized and coarse highly oriented non-dynamic recrystallized grains. Rare-earth atoms are in solid solution after extrusion at 400 °C and precipitation takes place during the thermal treatment at 200 °C. Precipitation of β’ prismatic plates and lamellar γ’ in the basal plane increases the tensile yield stress from 325 to 409 MPa. During equal channel angular pressing processing at 300 °C, the volume fraction of dynamic recrystallized grains continuously increases with the strain introduced during the equal channel angular pressing proce...

International Journal of Plasticity, 2018

The effect of the orientation of the non-recrystallized grains (non-DRX) and the LPSO phase on pl... more The effect of the orientation of the non-recrystallized grains (non-DRX) and the LPSO phase on plasticity in extruded Mg97Y2Zn1 alloy with a bimodal grain structure have been studied in-situ using the combination of synchrotron diffraction and acoustic emission techniques during compression tests. The adaptive sequential k-means (ASK) procedure was applied to analyze the acoustic emission signal. This method can successful separate the signal for each possible deformation systems. Combining both techniques the deformation mechanisms that take place during the compression tests under different loading directions have been distinguish. Independently of the loading direction, the beginning of the macroscopic plasticity is always controlled by the activation of basal slip system in the DRX grains. However, highly oriented non-DRX grains and LPSO phase have a strong influence over the compressive deformation of the MgY2Zn1 alloy. The basal planes in the non-DRX grains were oriented parallel to the extrusion direction (ED). Thus, the activation of the extension twinning was found to be significant only in the ED mode. In the other two loading cases, TD and 45, the activation of non-basal slip systems has been detected. On the other hand, the reinforcing effect of the   1012 1011 2 elongated LPSO phase is the most effective, if the loading axis is aligned with the fiber direction (extrusion direction) since the load transfer mechanism is more effective. In this loading case, the LPSO can be plastically deformed due to kinking. This deformation mode has been isolated by the ASK procedure and characterized by in-situ scanning electron microscopy.

Materials (Basel, Switzerland), Jan 5, 2018

Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equa... more Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equal channel angular pressing (ECAP) have been considered for effective methods of maintaining the high mechanical strength of Mg-Y-Zn alloys containing long-period stacking ordered structures with respect to the alloy processed by the conventional extrusion of as-cast ingots with the advantage of minimizing the yttrium content. A yield stress similar to that found for extruded MgY₂Zn₁ alloy can be attained with only half of the usual yttrium and zinc additions thanks to the grain refinement induced by ECAP processing. The properties of MgY₁Zn subjected to ECAP are maintained up to 200 °C, but superplastic behavior is found above this temperature when the alloy is processed through a powder metallurgy route.

Revista de Metalurgia, 2015

The lineal thermal expansion coefficient of the 18R Long-Period Stacking Ordered (LPSO) structure... more The lineal thermal expansion coefficient of the 18R Long-Period Stacking Ordered (LPSO) structure was determined in the range between room temperature and 400 °C by dilatometry and synchrotron radiation diffraction. Results clearly show that the lineal thermal expansion coefficients for magnesium and the LPSO phase are similar and therefore no mismatch thermal stresses are generated at their interface in two-phase Mg-Y-Zn alloys containing this phase during thermomechanical processing.

Revista de Metalurgia, 2005

10 % en volumen, de cromo en las propiedades mecánicas de aleaciones NÍ3Al'Cr procesadas por vía ... more 10 % en volumen, de cromo en las propiedades mecánicas de aleaciones NÍ3Al'Cr procesadas por vía pulvimetalúrgica. Para ello se prepararon dos aleaciones: la primera, se obtuvo por molienda de polvo de composición Ni-20,9Al-8Cr'0,49B (% at.) y, a la segunda, se le añadió un 10 % en volumen de partículas de cromo, mediante un proceso de mezcla, previo al de molienda. Ambas, fueron consolidadas mediante compactación isostática en caliente (HIP) y, por último, se les aplicaron tratamientos térmicos para homogeneizar la microestructura. Los resultados experimentales han mostrado que el refuerzo de cromo tiene como efecto un importante aumento del límite elástico y de la resistencia.. Así, el material reforzado presenta un límite elástico cercano a 1.300 MPa, a temperatura ambiente, frente a los 800 MPa que presenta el material sin reforzar, a la misma temperatura. En relación con las propiedades mecánicas de los materiales tratados térmicamente, se observa que ambos experimentan un acusado descenso de la ductilidad y de la resistencia máxima a la tracción. Palabras clave NÍ3AL Microestructura. Propiedades mecánicas. Pulvimetalurgia. Effect of the addition of 10 % (volume fraction) of chromium on the mechanical properties of NiAICr processed by powder metallurgy

Revista de Metalurgia, 2005

Resumen En este trabajo se estudia la evolución de las propiedades mecánicas con la temperatura, ... more Resumen En este trabajo se estudia la evolución de las propiedades mecánicas con la temperatura, mediante ensayos de tracción, de dos aleaciones amorfas Mg'23Ni y Mg'35Ni (% en masa) procesadas por solidificación rápida. Las dos aleaciones experimentan, en el intervalo de temperaturas de ensayo (temperatura ambiente'350 °C), procesos de cristalización que transcurren en dos etapas, en el caso de la aleación Mg'23Ni, y en una etapa, en la aleación Mg'35Ni. Los cambios microestructurales asociados a los procesos de cristalización son responsables de la variación de las propiedades mecánicas con la temperatura así como de las diferencias observadas entre las dos aleaciones. Palabras clave Aleaciones de magnesio. Amorfos. Propiedades mecánicas.

Revista de Metalurgia, 2006

Vidrios metálicos. Aleaciones de magnesio. Propiedades mecánicas.

En este trabajo se ha estudiado el efecto de la adición de nanofibras de carbono en las propiedad... more En este trabajo se ha estudiado el efecto de la adición de nanofibras de carbono en las propiedades mecánicas de la aleación AZ31 procesada por una ruta pulvimetalúrgica convencional. Se prepararon tres materiales, AZ31, AZ31-1 % C y AZ31-2 % C. Tras una mezcla mecánica de las nanofibras con los polvos de AZ31, se precompactaron en frío y se extruyeron a 350°C. Los tres presentan una microestructura recristalizada con un tamaño de grano similar, fino aunque algo heterogéneo. Los tres materiales presentan una débil textura de fibra con el plano basal paralelo a la dirección de extrusión. Las propiedades mecánicas a tracción únicamente se ven afectadas por la presencia de nanofibras a 100°C superando los materiales reforzados en un 30 % a los valores de límite elástico y resistencia de la aleación sin reforzar.

Trabajo recibido el día 4 de marzo de 2013 y aceptado en su forma final el día 7 de mayo de 2013.

Strength of Materials, 2008

A detailed knowledge o f dependence o f mechanical properties on orientation in materials prepare... more A detailed knowledge o f dependence o f mechanical properties on orientation in materials prepared by directional processes may present an important fa cto r influencing the design o f construction parts. Toward this end, the compressive creep testing o f short specimens may be useful. Three different magnesium-based materials were subjected to this testing: (i) pure magnesium, (ii) magnesium matrix composite reinforced with 10 vol.% o f titanium, and (iii) magnesium alloy WE54. A ll three materials were prepared through a pow der metallurgical route with fin a l hot extrusion. The specimens fo r creep tests were cut in such a way that their longitudinal axis (i.e., the direction o f compressive creep stress) and the axis o f extruded bar contained a predestined angle. Two extreme cases can be observed: In pure M g and in M g-T i composite, the dependence o f the creep rate is very sensitive to the orientation especially at small inclinations from extrusion axis. The greatest creep resistance is observed in specimens with stress axis parallel to the extrusion axis, the lowest at declinations from 45 to 90°. On the other hand, in WE54 no orientation dependence was observed. Possible explanations o f the behaviour based on microstructural observations are discussed. K e y w o r d s : m agn esiu m , creep, com p osite, texture. In tr o d u c tio n. M icrostructure o f m an y m aterials-either in ten tion ally or o w in g to production history-is not isotropic. C onsequently, m ech an ical properties are not

Revista de Metalurgia, 2005

Resumen El presente estudio trata sobre la caracterización mecánica, en el intervalo de temperatu... more Resumen El presente estudio trata sobre la caracterización mecánica, en el intervalo de temperaturas comprendido entre 25 y 300 °C, del material compuesto de matriz magnesio Mg-lOTí (% vol.) obtenido a través de una ruta pulvimetalúrgica que incluye la mezcla de los polvos de magnesio y titanio, compactación en frío y extrusión a 400 °C. El material muestra una elevada resistencia (218 MPa) y alargamiento (4,7 %) a temperatura ambiente, valores superiores a los de la mayoría de materiales compuestos de matriz magnesio reforzados con un material cerámico. La reducción en las propiedades mecánicas del material se produce de un modo gradual a partir de 100 °C, lo que indica el efecto beneficioso del refuerzo de titanio.

Scripta Materialia, 2009

... References. [1] MD Nave and MR Barnett. Scripta Mater., 51 (2004), p. 881. [2] H. Somekawa an... more ... References. [1] MD Nave and MR Barnett. Scripta Mater., 51 (2004), p. 881. [2] H. Somekawa and T. Mukai. ... [5] J. Bohlen, MR Nürnberg, JW Senn, D. Letzig and SR Agnew. Acta Mater., 55 (2007), p. 2101. [6] N. Stanford and M. Barnett. Scripta Mater., 58 (2008), p. 179. ...

Metallurgical and Materials Transactions A, 2012

High performance Mg-6Al-3Sn-0.25Mn-xZn alloys (x = 0, 0.5, 1.0, 1.5, and 2.0 wt %) without rare e... more High performance Mg-6Al-3Sn-0.25Mn-xZn alloys (x = 0, 0.5, 1.0, 1.5, and 2.0 wt %) without rare earth were designed. The effects of different Zn contents on the microstructure and mechanical properties were systematically investigated. The addition of Zn obviously refines the as-cast alloys dendritic structure because of the increase in the number in the second phase. For the as-extruded alloys, an appropriate amount of Zn promotes complete recrystallization, thus increasing the grain size. As the Zn content increases, the texture gradually evolves into a typical strong basal texture, which means that the basal slip is difficult to initiate. Meanwhile, the addition of Zn promotes the precipitation of small-sized second phases, which can hinder the dislocation movement. The combination of texture strengthening and precipitation strengthening is the main reason for the improvement of alloys' strength.

Materials Science and Engineering: A, 2012

ABSTRACT The creep resistance of the Mg97Y2Zn1 (at.%) alloy in the as-cast condition and after a ... more ABSTRACT The creep resistance of the Mg97Y2Zn1 (at.%) alloy in the as-cast condition and after a isochronal thermal treatment up to 560 °C is evaluated from 200 °C to 350 °C. The as-cast alloy shows a microstructure characterized by magnesium dendrites and a Long-Period Stacking Ordered Structure in the interdendritic regions. The heat treated alloy shows a fully lamellar structure within magnesium grains. In both cases, the stress dependence of the creep rate presents two different regions. For low temperature and/or high strain rates, the creep behaviour shows a high stress exponent (n = 11) and high activation energy. The alloy behaves as a metal matrix composite where the magnesium matrix transfers part of its load to the LPSO-phase. Moreover, the lamellar structure within the magnesium grains in the thermal treated alloy results in an additional barrier against creep deformation. At high temperature and/or low strain rates, creep is controlled by non-basal dislocation slip. The cast alloy showed higher creep resistance than the heat treated alloy at low stresses since the diffusion of Zn and Y atoms nucleate at Shockley partial dislocations inhibiting their movements.

Materials Science and Engineering: A, 2007

The effect of the extrusion temperature on the microstructure and mechanical behaviour of the pow... more The effect of the extrusion temperature on the microstructure and mechanical behaviour of the powder metallurgy WE54 alloy has been investigated between 300 and 400 • C. After extrusion, the microstructure consists of magnesium grains and Mg 14 YNd 2 particles located at grain boundaries. The alloy exhibits superplastic behaviour at high strain rates, attaining elongations to failure around 500%.

Journal of Materials Science, 2007

In the present work the influence of texture on the mechanical properties up to 500 °C of commerc... more In the present work the influence of texture on the mechanical properties up to 500 °C of commercially pure magnesium prepared by PM was determined. Extrusion of magnesium powders was carried out between 250 and 450 °C. All extruded materials exhibited an intense fibre texture with the basal planes parallel to the extrusion direction whose intensity increased in line with the

Journal of Materials Science, 2014

Journal of Alloys and Compounds, 2007

El artículo seleccionado no se encuentra disponible por ahora a texto completo por no haber sido ... more El artículo seleccionado no se encuentra disponible por ahora a texto completo por no haber sido facilitado todavía por el investigador a cargo del archivo del mismo.

Metals, 2020

The corrosion behaviour of Mg98.5-Nd1-Zn0.5 (at. %) alloy was studied in phosphate buffered salin... more The corrosion behaviour of Mg98.5-Nd1-Zn0.5 (at. %) alloy was studied in phosphate buffered saline (PBS) solution to evaluate its degradation performance as a potential candidate for biomedical applications. The alloy, produced by casting and hot extrusion, consists of a fine-grained magnesium matrix with an average grain size of 3.8 μm embedding a high volume fraction of (Mg, Zn)12Nd precipitates. Hydrogen release tests revealed a stable low corrosion rate of 0.6 mm/year after 24 h of immersion. Electrochemical testing data proved good correlation with the data from hydrogen evolution, with the corrosion rate stabilizing below 1 mm/year.

Metals, 2019

The evolution of the microstructure and mechanical properties during equal channel angular pressi... more The evolution of the microstructure and mechanical properties during equal channel angular pressing processing has been studied in an extruded Mg-Gd-Y-Zn alloy containing long-period stacking ordered phases. After extrusion, the microstructure is characterized by the presence of long-period stacking ordered fibers elongated along the extrusion direction within the magnesium matrix. The grain structure is a mixture of randomly oriented dynamic recrystallized and coarse highly oriented non-dynamic recrystallized grains. Rare-earth atoms are in solid solution after extrusion at 400 °C and precipitation takes place during the thermal treatment at 200 °C. Precipitation of β’ prismatic plates and lamellar γ’ in the basal plane increases the tensile yield stress from 325 to 409 MPa. During equal channel angular pressing processing at 300 °C, the volume fraction of dynamic recrystallized grains continuously increases with the strain introduced during the equal channel angular pressing proce...

International Journal of Plasticity, 2018

The effect of the orientation of the non-recrystallized grains (non-DRX) and the LPSO phase on pl... more The effect of the orientation of the non-recrystallized grains (non-DRX) and the LPSO phase on plasticity in extruded Mg97Y2Zn1 alloy with a bimodal grain structure have been studied in-situ using the combination of synchrotron diffraction and acoustic emission techniques during compression tests. The adaptive sequential k-means (ASK) procedure was applied to analyze the acoustic emission signal. This method can successful separate the signal for each possible deformation systems. Combining both techniques the deformation mechanisms that take place during the compression tests under different loading directions have been distinguish. Independently of the loading direction, the beginning of the macroscopic plasticity is always controlled by the activation of basal slip system in the DRX grains. However, highly oriented non-DRX grains and LPSO phase have a strong influence over the compressive deformation of the MgY2Zn1 alloy. The basal planes in the non-DRX grains were oriented parallel to the extrusion direction (ED). Thus, the activation of the extension twinning was found to be significant only in the ED mode. In the other two loading cases, TD and 45, the activation of non-basal slip systems has been detected. On the other hand, the reinforcing effect of the   1012 1011 2 elongated LPSO phase is the most effective, if the loading axis is aligned with the fiber direction (extrusion direction) since the load transfer mechanism is more effective. In this loading case, the LPSO can be plastically deformed due to kinking. This deformation mode has been isolated by the ASK procedure and characterized by in-situ scanning electron microscopy.

Materials (Basel, Switzerland), Jan 5, 2018

Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equa... more Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equal channel angular pressing (ECAP) have been considered for effective methods of maintaining the high mechanical strength of Mg-Y-Zn alloys containing long-period stacking ordered structures with respect to the alloy processed by the conventional extrusion of as-cast ingots with the advantage of minimizing the yttrium content. A yield stress similar to that found for extruded MgY₂Zn₁ alloy can be attained with only half of the usual yttrium and zinc additions thanks to the grain refinement induced by ECAP processing. The properties of MgY₁Zn subjected to ECAP are maintained up to 200 °C, but superplastic behavior is found above this temperature when the alloy is processed through a powder metallurgy route.

Revista de Metalurgia, 2015

The lineal thermal expansion coefficient of the 18R Long-Period Stacking Ordered (LPSO) structure... more The lineal thermal expansion coefficient of the 18R Long-Period Stacking Ordered (LPSO) structure was determined in the range between room temperature and 400 °C by dilatometry and synchrotron radiation diffraction. Results clearly show that the lineal thermal expansion coefficients for magnesium and the LPSO phase are similar and therefore no mismatch thermal stresses are generated at their interface in two-phase Mg-Y-Zn alloys containing this phase during thermomechanical processing.

Revista de Metalurgia, 2005

10 % en volumen, de cromo en las propiedades mecánicas de aleaciones NÍ3Al'Cr procesadas por vía ... more 10 % en volumen, de cromo en las propiedades mecánicas de aleaciones NÍ3Al'Cr procesadas por vía pulvimetalúrgica. Para ello se prepararon dos aleaciones: la primera, se obtuvo por molienda de polvo de composición Ni-20,9Al-8Cr'0,49B (% at.) y, a la segunda, se le añadió un 10 % en volumen de partículas de cromo, mediante un proceso de mezcla, previo al de molienda. Ambas, fueron consolidadas mediante compactación isostática en caliente (HIP) y, por último, se les aplicaron tratamientos térmicos para homogeneizar la microestructura. Los resultados experimentales han mostrado que el refuerzo de cromo tiene como efecto un importante aumento del límite elástico y de la resistencia.. Así, el material reforzado presenta un límite elástico cercano a 1.300 MPa, a temperatura ambiente, frente a los 800 MPa que presenta el material sin reforzar, a la misma temperatura. En relación con las propiedades mecánicas de los materiales tratados térmicamente, se observa que ambos experimentan un acusado descenso de la ductilidad y de la resistencia máxima a la tracción. Palabras clave NÍ3AL Microestructura. Propiedades mecánicas. Pulvimetalurgia. Effect of the addition of 10 % (volume fraction) of chromium on the mechanical properties of NiAICr processed by powder metallurgy

Revista de Metalurgia, 2005

Resumen En este trabajo se estudia la evolución de las propiedades mecánicas con la temperatura, ... more Resumen En este trabajo se estudia la evolución de las propiedades mecánicas con la temperatura, mediante ensayos de tracción, de dos aleaciones amorfas Mg'23Ni y Mg'35Ni (% en masa) procesadas por solidificación rápida. Las dos aleaciones experimentan, en el intervalo de temperaturas de ensayo (temperatura ambiente'350 °C), procesos de cristalización que transcurren en dos etapas, en el caso de la aleación Mg'23Ni, y en una etapa, en la aleación Mg'35Ni. Los cambios microestructurales asociados a los procesos de cristalización son responsables de la variación de las propiedades mecánicas con la temperatura así como de las diferencias observadas entre las dos aleaciones. Palabras clave Aleaciones de magnesio. Amorfos. Propiedades mecánicas.

Revista de Metalurgia, 2006

Vidrios metálicos. Aleaciones de magnesio. Propiedades mecánicas.

En este trabajo se ha estudiado el efecto de la adición de nanofibras de carbono en las propiedad... more En este trabajo se ha estudiado el efecto de la adición de nanofibras de carbono en las propiedades mecánicas de la aleación AZ31 procesada por una ruta pulvimetalúrgica convencional. Se prepararon tres materiales, AZ31, AZ31-1 % C y AZ31-2 % C. Tras una mezcla mecánica de las nanofibras con los polvos de AZ31, se precompactaron en frío y se extruyeron a 350°C. Los tres presentan una microestructura recristalizada con un tamaño de grano similar, fino aunque algo heterogéneo. Los tres materiales presentan una débil textura de fibra con el plano basal paralelo a la dirección de extrusión. Las propiedades mecánicas a tracción únicamente se ven afectadas por la presencia de nanofibras a 100°C superando los materiales reforzados en un 30 % a los valores de límite elástico y resistencia de la aleación sin reforzar.

Trabajo recibido el día 4 de marzo de 2013 y aceptado en su forma final el día 7 de mayo de 2013.

Strength of Materials, 2008

A detailed knowledge o f dependence o f mechanical properties on orientation in materials prepare... more A detailed knowledge o f dependence o f mechanical properties on orientation in materials prepared by directional processes may present an important fa cto r influencing the design o f construction parts. Toward this end, the compressive creep testing o f short specimens may be useful. Three different magnesium-based materials were subjected to this testing: (i) pure magnesium, (ii) magnesium matrix composite reinforced with 10 vol.% o f titanium, and (iii) magnesium alloy WE54. A ll three materials were prepared through a pow der metallurgical route with fin a l hot extrusion. The specimens fo r creep tests were cut in such a way that their longitudinal axis (i.e., the direction o f compressive creep stress) and the axis o f extruded bar contained a predestined angle. Two extreme cases can be observed: In pure M g and in M g-T i composite, the dependence o f the creep rate is very sensitive to the orientation especially at small inclinations from extrusion axis. The greatest creep resistance is observed in specimens with stress axis parallel to the extrusion axis, the lowest at declinations from 45 to 90°. On the other hand, in WE54 no orientation dependence was observed. Possible explanations o f the behaviour based on microstructural observations are discussed. K e y w o r d s : m agn esiu m , creep, com p osite, texture. In tr o d u c tio n. M icrostructure o f m an y m aterials-either in ten tion ally or o w in g to production history-is not isotropic. C onsequently, m ech an ical properties are not

Revista de Metalurgia, 2005

Resumen El presente estudio trata sobre la caracterización mecánica, en el intervalo de temperatu... more Resumen El presente estudio trata sobre la caracterización mecánica, en el intervalo de temperaturas comprendido entre 25 y 300 °C, del material compuesto de matriz magnesio Mg-lOTí (% vol.) obtenido a través de una ruta pulvimetalúrgica que incluye la mezcla de los polvos de magnesio y titanio, compactación en frío y extrusión a 400 °C. El material muestra una elevada resistencia (218 MPa) y alargamiento (4,7 %) a temperatura ambiente, valores superiores a los de la mayoría de materiales compuestos de matriz magnesio reforzados con un material cerámico. La reducción en las propiedades mecánicas del material se produce de un modo gradual a partir de 100 °C, lo que indica el efecto beneficioso del refuerzo de titanio.

Scripta Materialia, 2009

... References. [1] MD Nave and MR Barnett. Scripta Mater., 51 (2004), p. 881. [2] H. Somekawa an... more ... References. [1] MD Nave and MR Barnett. Scripta Mater., 51 (2004), p. 881. [2] H. Somekawa and T. Mukai. ... [5] J. Bohlen, MR Nürnberg, JW Senn, D. Letzig and SR Agnew. Acta Mater., 55 (2007), p. 2101. [6] N. Stanford and M. Barnett. Scripta Mater., 58 (2008), p. 179. ...

Metallurgical and Materials Transactions A, 2012

High performance Mg-6Al-3Sn-0.25Mn-xZn alloys (x = 0, 0.5, 1.0, 1.5, and 2.0 wt %) without rare e... more High performance Mg-6Al-3Sn-0.25Mn-xZn alloys (x = 0, 0.5, 1.0, 1.5, and 2.0 wt %) without rare earth were designed. The effects of different Zn contents on the microstructure and mechanical properties were systematically investigated. The addition of Zn obviously refines the as-cast alloys dendritic structure because of the increase in the number in the second phase. For the as-extruded alloys, an appropriate amount of Zn promotes complete recrystallization, thus increasing the grain size. As the Zn content increases, the texture gradually evolves into a typical strong basal texture, which means that the basal slip is difficult to initiate. Meanwhile, the addition of Zn promotes the precipitation of small-sized second phases, which can hinder the dislocation movement. The combination of texture strengthening and precipitation strengthening is the main reason for the improvement of alloys' strength.

Materials Science and Engineering: A, 2012

ABSTRACT The creep resistance of the Mg97Y2Zn1 (at.%) alloy in the as-cast condition and after a ... more ABSTRACT The creep resistance of the Mg97Y2Zn1 (at.%) alloy in the as-cast condition and after a isochronal thermal treatment up to 560 °C is evaluated from 200 °C to 350 °C. The as-cast alloy shows a microstructure characterized by magnesium dendrites and a Long-Period Stacking Ordered Structure in the interdendritic regions. The heat treated alloy shows a fully lamellar structure within magnesium grains. In both cases, the stress dependence of the creep rate presents two different regions. For low temperature and/or high strain rates, the creep behaviour shows a high stress exponent (n = 11) and high activation energy. The alloy behaves as a metal matrix composite where the magnesium matrix transfers part of its load to the LPSO-phase. Moreover, the lamellar structure within the magnesium grains in the thermal treated alloy results in an additional barrier against creep deformation. At high temperature and/or low strain rates, creep is controlled by non-basal dislocation slip. The cast alloy showed higher creep resistance than the heat treated alloy at low stresses since the diffusion of Zn and Y atoms nucleate at Shockley partial dislocations inhibiting their movements.

Materials Science and Engineering: A, 2007

The effect of the extrusion temperature on the microstructure and mechanical behaviour of the pow... more The effect of the extrusion temperature on the microstructure and mechanical behaviour of the powder metallurgy WE54 alloy has been investigated between 300 and 400 • C. After extrusion, the microstructure consists of magnesium grains and Mg 14 YNd 2 particles located at grain boundaries. The alloy exhibits superplastic behaviour at high strain rates, attaining elongations to failure around 500%.

Journal of Materials Science, 2007

In the present work the influence of texture on the mechanical properties up to 500 °C of commerc... more In the present work the influence of texture on the mechanical properties up to 500 °C of commercially pure magnesium prepared by PM was determined. Extrusion of magnesium powders was carried out between 250 and 450 °C. All extruded materials exhibited an intense fibre texture with the basal planes parallel to the extrusion direction whose intensity increased in line with the

Journal of Materials Science, 2014

Journal of Alloys and Compounds, 2007

El artículo seleccionado no se encuentra disponible por ahora a texto completo por no haber sido ... more El artículo seleccionado no se encuentra disponible por ahora a texto completo por no haber sido facilitado todavía por el investigador a cargo del archivo del mismo.