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Haroldo Cavalcanti Pinto - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ce-base Mischmetal addition on the microstructure and mechanical properties of hot-rolled ZK60 alloy
Journal of Magnesium and Alloys, 2020Co-Authors: Erenilton Pereira Da Silva, Ricardo Henrique Buzolin, F. Marques, Flavio Soldera, U. Alfaro, Haroldo Cavalcanti PintoAbstract:Abstract Mg-Zn-Zr (ZK) alloys exhibit notably high mechanical strength amongst all magnesium alloy grades. However, due to the formation of low melting point Mg3Zn7-precipitates, these alloys are susceptible to hot cracking, thus compromising their metallurgical processing. The addition of rare earths to ZK alloys is an alternative to form higher melting point intermetallic compounds, speed up dynamic recrystallization, refine grain size, enhance corrosion resistance and extend the service temperature due to improved creep resistance. This work deals with the effect of Ce-base Mischmetal addition on the hot rolling behaviour of as-cast ZK60 alloy. The microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg7Zn3 intermetallics occur during hot rolling, whereas no further precipitation is observed for the ZK60-Mm alloys. The fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg7Zn3 are observed for the ZK60, whereas Mg7Zn3 and MgZn2Ce intermetallics are formed in the alloy modified with Mischmetal addition. A higher fraction of dynamically recrystallized grains is observed for the ZK60-Mm in comparison to the ZK60. Continuous recrystallization takes place in ZK60 with the formation of sub-grains near to the intermetallics and the addition of Mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the precipitates. The mechanical strength and, in particular, the ductility of the hot-rolled alloys are notably improved when compared to the same alloys in the as-cast condition. The mechanical strength is, however, higher for the ZK60 alloy. Less solid solution strengthening, softer MgZn2Ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of ZK60-Mm. Failure in both alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions.
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Impact of Ce-base Mischmetal on the microstructure and mechanical behavior of ZK60 magnesium casting alloys
Materials Science and Engineering: A, 2018Co-Authors: Erenilton Pereira Da Silva, F. Marques, U. Alfaro, T.s. Nossa, Haroldo Cavalcanti PintoAbstract:Abstract Magnesium alloys are important alternatives for structural weight reduction due to their low density and good specific mechanical strength. Among the magnesium alloys, the ZK type exhibits the highest mechanical strength. However, it has limitations on hot working or welding owing to the presence of intermetallics with low melting point and consequently susceptibility to hot crack formation. The addition of rare earths tends to form intermetallics with higher melting points, thus inhibiting the formation of hot cracks, as well as building up thin and dense surface films that improve corrosion resistance. This work studies the addition of 1.5% wt. of Mischmetal (Mm) to the ZK60 alloy, and then demonstrates the effects of the casting process with mechanical mixing in the semi-solid state. The alloys produced were: ZK60 and ZK60–1.5 wt%Mm manufactured by conventional casting and rheocast ZK60–1.5 wt%Mm produced with mechanical mixing in the semi-solid state. The casting and cooling methods result in defect-free and chemically homogeneous materials, and the mechanical mixing provides a homogeneous microstructure with globular grains. The mechanical strength was though higher for the ZK60 alloy due to its increased solute content within the Mg-matrix and the smaller quantity of intermetallics that builds up an intermittent network. The Mg7Zn3 intermetallic, which is the main precipitate for ZK60 alloy, has hardness 20% higher than the MgZn2Ce intermetallic that is precipitated with the Mischmetal addition and partly removes solute from the Mg-solid solution.
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severely deformed zk60 2 5 mm alloy for hydrogen storage produced by two different processing routes
International Journal of Hydrogen Energy, 2016Co-Authors: Juliano Soyama, Erenilton Pereira Da Silva, Haroldo Cavalcanti Pinto, Daniel Rodrigo Leiva, Alberto Moreira Jorge, Claudemiro Bolfarini, Claudio Shyinti Kiminami, Ricardo Floriano, Y Guo, W J BottaAbstract:Abstract In this investigation the commercial ZK60 magnesium alloy modified with 2.5 wt.% of Mischmetal was processed by melt spinning (MS) and equal-channel angular pressing (ECAP), both followed by extensive cold rolling (CR). The results indicate that MS was effective to produce small grain sizes in the order of 700 nm, while specimens prepared only by ECAP reached about 50 μm. However, melt spun ribbons showed long activation (first hydrogenation) times of more than 30 h in contrast to ECAP, which took about 10 h. In addition, after the activation process, the hydrogen storage capacity of ECAP was poorer than MS (2.5 and 3.3 wt.% of H2, respectively). Additional processing by CR caused further grain refinement and breakage of intermetallic particles, as well as favoring crystallographic texture in the (002) direction. All these features promoted a significant improvement in the hydrogen storage capacity, and in the absorption kinetics of the specimens processed by MS and ECAP.
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hydrogen storage in heavily deformed zk60 alloy modified with 2 5 wt mm addition
International Journal of Hydrogen Energy, 2016Co-Authors: Juliano Soyama, Erenilton Pereira Da Silva, Haroldo Cavalcanti Pinto, Maria Regina Martins Triques, Daniel Rodrigo Leiva, Alberto Moreira Jorge, Claudemiro Bolfarini, Claudio Shyinti Kiminami, W J BottaAbstract:Abstract Severe plastic deformation techniques have been extensively used to improve hydrogen storage properties of magnesium based alloys. In this work, the commercial magnesium alloy ZK60 (Mg-6Zn-1Zr in wt.%) was modified with addition of 2.5 wt.% of Mischmetal (55Ce-24La-15Nd-4Pr in wt.%) and subsequently processed by equal-channel angular pressing (ECAP) and extensive cold rolling (CR). Due to the Mischmetal addition, a network of intermetallic particles was formed at the grain boundaries. Besides Zn and Zr, the particles also contained the rare-earth elements La and Ce. With CR, a breakage of intermetallics occurred, that could also have played a role in enhancing the hydrogen storage properties. Ultimately, after the combined processing of ECAP followed by CR cold rolling, a significant increase in the storage capacity and activation kinetics was observed.
Erenilton Pereira Da Silva - One of the best experts on this subject based on the ideXlab platform.
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Effect of Ce-base Mischmetal addition on the microstructure and mechanical properties of hot-rolled ZK60 alloy
Journal of Magnesium and Alloys, 2020Co-Authors: Erenilton Pereira Da Silva, Ricardo Henrique Buzolin, F. Marques, Flavio Soldera, U. Alfaro, Haroldo Cavalcanti PintoAbstract:Abstract Mg-Zn-Zr (ZK) alloys exhibit notably high mechanical strength amongst all magnesium alloy grades. However, due to the formation of low melting point Mg3Zn7-precipitates, these alloys are susceptible to hot cracking, thus compromising their metallurgical processing. The addition of rare earths to ZK alloys is an alternative to form higher melting point intermetallic compounds, speed up dynamic recrystallization, refine grain size, enhance corrosion resistance and extend the service temperature due to improved creep resistance. This work deals with the effect of Ce-base Mischmetal addition on the hot rolling behaviour of as-cast ZK60 alloy. The microstructure investigation conducted using electron microscopy and X-Ray diffraction shows that precipitation of Mg7Zn3 intermetallics occur during hot rolling, whereas no further precipitation is observed for the ZK60-Mm alloys. The fragmentation of the intermetallic compounds occur during hot rolling and finer particles of Mg7Zn3 are observed for the ZK60, whereas Mg7Zn3 and MgZn2Ce intermetallics are formed in the alloy modified with Mischmetal addition. A higher fraction of dynamically recrystallized grains is observed for the ZK60-Mm in comparison to the ZK60. Continuous recrystallization takes place in ZK60 with the formation of sub-grains near to the intermetallics and the addition of Mischmetal promotes the occurrence of discontinuous recrystallization with the nucleation of new grains close to the precipitates. The mechanical strength and, in particular, the ductility of the hot-rolled alloys are notably improved when compared to the same alloys in the as-cast condition. The mechanical strength is, however, higher for the ZK60 alloy. Less solid solution strengthening, softer MgZn2Ce intermetallics and more extensive recrystallization contribute to reduce the mechanical strength of ZK60-Mm. Failure in both alloys are initiated at coarse intermetallics and propagate through intermetallic-rich regions.
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Impact of Ce-base Mischmetal on the microstructure and mechanical behavior of ZK60 magnesium casting alloys
Materials Science and Engineering: A, 2018Co-Authors: Erenilton Pereira Da Silva, F. Marques, U. Alfaro, T.s. Nossa, Haroldo Cavalcanti PintoAbstract:Abstract Magnesium alloys are important alternatives for structural weight reduction due to their low density and good specific mechanical strength. Among the magnesium alloys, the ZK type exhibits the highest mechanical strength. However, it has limitations on hot working or welding owing to the presence of intermetallics with low melting point and consequently susceptibility to hot crack formation. The addition of rare earths tends to form intermetallics with higher melting points, thus inhibiting the formation of hot cracks, as well as building up thin and dense surface films that improve corrosion resistance. This work studies the addition of 1.5% wt. of Mischmetal (Mm) to the ZK60 alloy, and then demonstrates the effects of the casting process with mechanical mixing in the semi-solid state. The alloys produced were: ZK60 and ZK60–1.5 wt%Mm manufactured by conventional casting and rheocast ZK60–1.5 wt%Mm produced with mechanical mixing in the semi-solid state. The casting and cooling methods result in defect-free and chemically homogeneous materials, and the mechanical mixing provides a homogeneous microstructure with globular grains. The mechanical strength was though higher for the ZK60 alloy due to its increased solute content within the Mg-matrix and the smaller quantity of intermetallics that builds up an intermittent network. The Mg7Zn3 intermetallic, which is the main precipitate for ZK60 alloy, has hardness 20% higher than the MgZn2Ce intermetallic that is precipitated with the Mischmetal addition and partly removes solute from the Mg-solid solution.
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Casting, rolling and friction stir welding in magnesium alloys with Mischmetal addition
'Universidade de Sao Paulo Agencia USP de Gestao da Informacao Academica (AGUIA)', 2017Co-Authors: Erenilton Pereira Da SilvaAbstract:A crescente escassez de recursos energéticos renováveis bem como o aumento contínuo dos seus custos, tem requerido uma redução drástica no consumo de energia utilizada para o transporte de cargas e passageiros nas últimas décadas. Uma alternativa é a redução de peso com a utilização de ligas leves em substituição às ligas convencionais utilizadas no setor de transporte. Nesse conceito o uso de ligas de magnésio é justificado pela sua baixa densidade. Dentre as ligas de magnésio, a matriz ASTM série ZK é a que apresenta maior resistência mecânica e a adição de elementos de terras raras (RE) elevam a resistência à corrosão, a temperatura de trabalho e o limite de escoamento, devido à formação de filmes de óxidos finos e densos, além de intermetálicos de alto ponto de fusão e de maior dureza. A formação de intermetálicos do tipo MgZn de baixo ponto de fusão, torna as ligas de matriz do tipo ZK susceptíveis à formação de trinca à quente durante a soldagem, inviabilizando o uso de processos de soldagem convencionais. Uma alternativa é a solda por fricção e mistura mecânica (SFMM) realizada abaixo da temperatura de fusão. Neste trabalho, foram produzidas ligas ZK60, ZK60-1,5RE (liga ZK60 com adição de 1,5% em peso de Mischmetal) por fundição convencional e ZK60-1,5RE tixofundidas com batimento mecânico no estado semissólido. Todas foram laminadas a quente em um laminador simétrico e soldadas por fricção e mistura mecânica. Os métodos de fundição e resfriamento apresentaram materiais isentos de defeitos e com homogeneidade química, além do batimento mecânico proporcionar uma microestrutura com grãos globulares homogêneos. A adição de Mischmetal deu origem a uma microestrutura com granulometria aproximadamente 22% menor. Quando comparado com o método de fundição, a liga fundida com batimento no estado semissólido apresentou uma diminuição no tamanho médio de grão de aproximadamente 26%. A laminação deu origem a uma microestrutura parcialmente recristalizada, com tamanho médio de grãos entre 3 e 4 μm. A rede de intermetálicos foi quebrada, porém, manteve-se contínua para as ligas com adição de Mm. Quanto à resistência mecânica, a liga ZK60 foi superior, devido à menor quantidade e redes intermitentes de intermetálicos, uma vez que tanto para as ligas fundidas quanto para as laminadas, as trincas foram originadas nas regiões de aglomeração de intermetálicos. As ligas com adição de Mm apresentaram melhor estabilidade térmica durante a soldagem e melhor acabamento superficial, sendo possível a soldagem com rotação de 1200 rpm e velocidade de avanço de 400 mm/min enquanto a liga ZK60 só foi possível a soldagem com 200 mm/min. As análises das tensões residuais apresentaram valores e perfis semelhantes e seguem o fluxo de material, bem como a textura dos cordões de solda. Os mapas de microdureza na secção transversal do cordão de solda revelaram maior dureza nas zonas de mistura, e valores ainda maiores e mais homogêneos para liga ZK60, pode-se afirmar que os intermetálicos do tipo MgZn tem maior dureza que os do tipo MgZnRE.The growing scarcity of renewable energy resources, as well as the continued rise in costs has required in recent decades a dramatic reduction in energy used for transportation freight and passenger, which is increasing daily all over the world. An alternative is to weight reduction with the use of light alloys, this concept the use of magnesium alloys is justified by their low density, about 1/3 lower than that of aluminum. Among the magnesium alloy, the matrix is ZK type that has greater mechanical strength and the addition of rare earth elements (RE) to increase corrosion resistance, working temperature and yield strength due to the formation of thin films and density oxides, and intermetallic of the high melting point and higher hardness. The formation of intermetallic of the MgZn type, which has a low melting point, makes alloys with matrix of the ZK type susceptible to formation of hot crack during the welding, making impossible the use of conventional welding processes, an alternative is the friction stir welding (FSW) that the union is made below the melting point. This work shows the studies the addition of 1.5% wt. of Mischmetal (Mm) in the ZK60 alloy and effects of the casting process with mechanical mixing in the semi-solid state. Were produced the alloys: ZK60, ZK60-1.5RE with conventional casting and ZK60-1.5RE Tixo with mechanical mixing in the semi-solid state, all were hot-rolled in a symmetrical laminator and welded with friction stir welding (FSW) process. The methods of casting and cooling gave resulted in materials free of defects and chemical homogeneity, and the mechanical mixing provides homogeneous microstructure with globular grains. The alloy with Mischmetal addition had an average grain size of about 22% lower than ZK60 alloy, when compared to the casting method the ZK60- 1.5RE Tixo alloy had an average grain size of about 26% lower than ZK60-1.5RE alloy. The rolling process gave rise to a partially recrystallized microstructure with average grain size of between 3.3 and 4.23 μm, the intermetallic network were broken, however, kept continuous for alloys with Mm addition. As for mechanical strength was higher for ZK60 alloy, due smaller amount and intermittent network of the intermetallic. The alloys with Mm addition had better thermal stability during welding and showed better surface quality, being possible to do a welding with rotation of 1200 rpm and advancing speed of 400 mm/min while the ZK60 alloy only was possible the welding with advancing speed of 200 mm/min. The analyzes of residual stresses had similar values and profiles and follow the flow of material as well as the texture of the weld beads. The micro hardness maps in the cross section of the weld bead showed a higher hardness in the mixing zones, and higher and more homogeneous values for ZK60 alloy, and can thus affirm that the intermetallic MgZn type has higher hardness than the MgZnRE type
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severely deformed zk60 2 5 mm alloy for hydrogen storage produced by two different processing routes
International Journal of Hydrogen Energy, 2016Co-Authors: Juliano Soyama, Erenilton Pereira Da Silva, Haroldo Cavalcanti Pinto, Daniel Rodrigo Leiva, Alberto Moreira Jorge, Claudemiro Bolfarini, Claudio Shyinti Kiminami, Ricardo Floriano, Y Guo, W J BottaAbstract:Abstract In this investigation the commercial ZK60 magnesium alloy modified with 2.5 wt.% of Mischmetal was processed by melt spinning (MS) and equal-channel angular pressing (ECAP), both followed by extensive cold rolling (CR). The results indicate that MS was effective to produce small grain sizes in the order of 700 nm, while specimens prepared only by ECAP reached about 50 μm. However, melt spun ribbons showed long activation (first hydrogenation) times of more than 30 h in contrast to ECAP, which took about 10 h. In addition, after the activation process, the hydrogen storage capacity of ECAP was poorer than MS (2.5 and 3.3 wt.% of H2, respectively). Additional processing by CR caused further grain refinement and breakage of intermetallic particles, as well as favoring crystallographic texture in the (002) direction. All these features promoted a significant improvement in the hydrogen storage capacity, and in the absorption kinetics of the specimens processed by MS and ECAP.
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hydrogen storage in heavily deformed zk60 alloy modified with 2 5 wt mm addition
International Journal of Hydrogen Energy, 2016Co-Authors: Juliano Soyama, Erenilton Pereira Da Silva, Haroldo Cavalcanti Pinto, Maria Regina Martins Triques, Daniel Rodrigo Leiva, Alberto Moreira Jorge, Claudemiro Bolfarini, Claudio Shyinti Kiminami, W J BottaAbstract:Abstract Severe plastic deformation techniques have been extensively used to improve hydrogen storage properties of magnesium based alloys. In this work, the commercial magnesium alloy ZK60 (Mg-6Zn-1Zr in wt.%) was modified with addition of 2.5 wt.% of Mischmetal (55Ce-24La-15Nd-4Pr in wt.%) and subsequently processed by equal-channel angular pressing (ECAP) and extensive cold rolling (CR). Due to the Mischmetal addition, a network of intermetallic particles was formed at the grain boundaries. Besides Zn and Zr, the particles also contained the rare-earth elements La and Ce. With CR, a breakage of intermetallics occurred, that could also have played a role in enhancing the hydrogen storage properties. Ultimately, after the combined processing of ECAP followed by CR cold rolling, a significant increase in the storage capacity and activation kinetics was observed.
John W Mandelman - One of the best experts on this subject based on the ideXlab platform.
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do rare earth metals deter spiny dogfish a feasibility study on the use of electropositive Mischmetal to reduce the bycatch of squalus acanthias by hook gear in the gulf of maine
Ices Journal of Marine Science, 2009Co-Authors: Shelly M L Tallack, John W MandelmanAbstract:Tallack, S. M. L., and Mandelman, J. W. 2009. Do rare-earth metals deter spiny dogfish? A feasibility study on the use of electropositive “Mischmetal” to reduce the bycatch of Squalus acanthias by hook gear in the Gulf of Maine. - ICES Journal of Marine Science, 66: 315-322.Catches of spiny dogfish (Squalus acanthias) are considered by commercial and recreational fishers to be unacceptably high during summer and autumn in the Gulf of Maine off the northeast coast of the USA. Consequently, there is interest in finding a dogfish deterrent for application in various fishing gears. Field studies tested triangular slices of the rare-earth metal cerium/lanthanide alloy (“Mischmetal”) incorporated into longlines and rod-and-reel gear to assess its effectiveness in reducing dogfish catches. Treatment catches (Mischmetal present) were compared with control (no Mischmetal) catches. Laboratory studies provided video-taped, behavioural observations on the effects of alloys under variable levels of food deprivation and dogfish density. No significant reductions in dogfish catch were recorded for either rod and reel or longline, and in situ video footage verified persistent dogfish feeding behaviour, regardless of Mischmetal presence. The laboratory trials found some evidence of avoidance behaviour in dogfish approaching treatment baits, but only with dogfish fed to satiation; no aversion to the material was observed after 2 and 4 d of food deprivation. Dogfish density had no effect on feeding behaviour in the laboratory. Overall, there is little evidence to suggest that Mischmetal can significantly reduce catches of dogfish in hook gears in the Gulf of Maine.
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do rare earth metals deter spiny dogfish a feasibility study on the use of electropositive Mischmetal to reduce the bycatch of squalus acanthias by hook gear in the gulf of maine
Ices Journal of Marine Science, 2009Co-Authors: Shelly M L Tallack, John W MandelmanAbstract:Tallack, S. M. L., and Mandelman, J. W. 2009. Do rare-earth metals deter spiny dogfish? A feasibility study on the use of electropositive “Mischmetal” to reduce the bycatch of Squalus acanthias by hook gear in the Gulf of Maine. - ICES Journal of Marine Science, 66: 315-322.Catches of spiny dogfish (Squalus acanthias) are considered by commercial and recreational fishers to be unacceptably high during summer and autumn in the Gulf of Maine off the northeast coast of the USA. Consequently, there is interest in finding a dogfish deterrent for application in various fishing gears. Field studies tested triangular slices of the rare-earth metal cerium/lanthanide alloy (“Mischmetal”) incorporated into longlines and rod-and-reel gear to assess its effectiveness in reducing dogfish catches. Treatment catches (Mischmetal present) were compared with control (no Mischmetal) catches. Laboratory studies provided video-taped, behavioural observations on the effects of alloys under variable levels of food deprivation and dogfish density. No significant reductions in dogfish catch were recorded for either rod and reel or longline, and in situ video footage verified persistent dogfish feeding behaviour, regardless of Mischmetal presence. The laboratory trials found some evidence of avoidance behaviour in dogfish approaching treatment baits, but only with dogfish fed to satiation; no aversion to the material was observed after 2 and 4 d of food deprivation. Dogfish density had no effect on feeding behaviour in the laboratory. Overall, there is little evidence to suggest that Mischmetal can significantly reduce catches of dogfish in hook gears in the Gulf of Maine.
P Adeva - One of the best experts on this subject based on the ideXlab platform.
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effects of calcium manganese and cerium rich Mischmetal additions on the mechanical properties of extruded mg zn y alloy reinforced by quasicrystalline i phase
Materials Characterization, 2017Co-Authors: J Medina, P Perez, G Garces, P AdevaAbstract:Abstract The effect of calcium, manganese and cerium Mischmetal additions on the mechanical properties of the extruded Mg-6Zn-1Y (wt%) alloy reinforced by quasicrystalline I-phase has been investigated. The tensile behaviour at room temperature can be rationalized on the basis of microstructural changes induced by the different elements added to the ternary alloy. The highest yield stress value corresponds to the material modified with cerium-rich Mischmetal. Manganese addition leads to the best balance between strength and ductility while calcium addition has a negligible effect on the mechanical properties of ternary alloy. The analysis of the contributions of the different strengthening mechanisms operating during deformation reveals that grain size refinement is the main hardening contribution in all alloys mechanism followed by the strengthening due to coarse second phases. The hardening due to basal texture conferred by the existence of coarse non-recrystallized grains depends on the overall hardening induced by the rest of strengthening mechanisms.
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microstructural changes in an extruded mgzny alloy reinforced by quasicrystalline i phase by small additions of calcium manganese and cerium rich Mischmetal
Materials Characterization, 2016Co-Authors: J Medina, P Perez, G Garces, D Tolnai, Andreas Stark, N Schell, P AdevaAbstract:Abstract The effects of calcium, manganese and cerium-rich Mischmetal additions on the microstructure and texture of the extruded Mg 6Zn 1Y (wt.%) alloy have been investigated. The microstructure of the alloys consisted of a magnesium matrix embedding second phase particles aligned along the extrusion direction. The nature and volume fraction of the second phases depended on the alloying element. Thus, Ce-rich Mischmetal promoted the formation of T-phase while calcium additions resulted in the formation of a ternary Mg Zn Ca compound. Only, manganese additions did not affect the existence of the I-phase present in the ternary alloy. The texture was measured and it was found that calcium addition has a significant effect weakening the extrusion texture.
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corrosion behaviour of mg zn y Mischmetal alloys in phosphate buffer saline solution
Corrosion Science, 2013Co-Authors: P Perez, P Adeva, E Onofre, Sandra Cabeza, I Llorente, J A Del Valle, M C Garciaalonso, M L EscuderoAbstract:Abstract The influence of the processing route and chemical composition in the corrosion behaviour of two Mg–Zn–Y–Mischmetal alloys has been evaluated in phosphate buffer saline solution. The corrosion resistance of the alloy processed by conventional techniques was substantially higher than that found for the same alloy processed from atomised powders. Fine homogeneous distribution of the second-phase particles promoted severe attack due to the enhanced number of galvanic microcells. A higher concentration of zinc and a lower content of rare earth additions improved the corrosion resistance of the alloys due to the lower volume fraction of second-phase particles.
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effect of Mischmetal substitution on the glass forming ability of mg ni la bulk metallic glasses
Intermetallics, 2009Co-Authors: S Gonzalez, I A Figueroa, H Zhao, H A Davies, I Todd, P AdevaAbstract:The effect of La substitution by LaMM (lanthanum Mischmetal) on the glass-forming ability of a Mg–Ni–La metallic glass has been studied. For compositions close to the eutectic Mg69Ni18La13, the LaMM substitution improved the glass-forming ability, for instance up to a critical amorphous diameter of 2 mm for the Mg65Ni20LaMM15 alloy. However, of all the alloys studied, it has been observed that La-containing alloys have higher GFA for compositions further from the eutectic and a maximum critical amorphous diameter of 2.5 mm was obtained for the Mg60Ni23.6La16.4 alloy.
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influence of Mischmetal composition on crystallization and mechanical properties of mg80 ni10 mm10 alloys
Intermetallics, 2009Co-Authors: P Perez, S Gonzalez, G Garces, P AdevaAbstract:The influence of Mischmetal composition, cerium- or lanthanum-rich, on crystallization and mechanical properties of amorphous Mg10Ni10MM10 alloys has been evaluated. The microstructure of the alloys consists of Mg17RE2 matrix (RE denotes a rare earth element) embedding other intermetallic phases whose compositions depend on the nature of Mischmetal addition. Major difference arises from the formation of Ni3RE in the alloy prepared with cerium-Mischmetal instead of the Mg2Ni phase crystallized in the lanthanum-Mischmetal-containing alloy. The mechanical behaviour, however, is very similar independently of the type of Mischmetal added.
P Perez - One of the best experts on this subject based on the ideXlab platform.
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effects of calcium manganese and cerium rich Mischmetal additions on the mechanical properties of extruded mg zn y alloy reinforced by quasicrystalline i phase
Materials Characterization, 2017Co-Authors: J Medina, P Perez, G Garces, P AdevaAbstract:Abstract The effect of calcium, manganese and cerium Mischmetal additions on the mechanical properties of the extruded Mg-6Zn-1Y (wt%) alloy reinforced by quasicrystalline I-phase has been investigated. The tensile behaviour at room temperature can be rationalized on the basis of microstructural changes induced by the different elements added to the ternary alloy. The highest yield stress value corresponds to the material modified with cerium-rich Mischmetal. Manganese addition leads to the best balance between strength and ductility while calcium addition has a negligible effect on the mechanical properties of ternary alloy. The analysis of the contributions of the different strengthening mechanisms operating during deformation reveals that grain size refinement is the main hardening contribution in all alloys mechanism followed by the strengthening due to coarse second phases. The hardening due to basal texture conferred by the existence of coarse non-recrystallized grains depends on the overall hardening induced by the rest of strengthening mechanisms.
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microstructural changes in an extruded mgzny alloy reinforced by quasicrystalline i phase by small additions of calcium manganese and cerium rich Mischmetal
Materials Characterization, 2016Co-Authors: J Medina, P Perez, G Garces, D Tolnai, Andreas Stark, N Schell, P AdevaAbstract:Abstract The effects of calcium, manganese and cerium-rich Mischmetal additions on the microstructure and texture of the extruded Mg 6Zn 1Y (wt.%) alloy have been investigated. The microstructure of the alloys consisted of a magnesium matrix embedding second phase particles aligned along the extrusion direction. The nature and volume fraction of the second phases depended on the alloying element. Thus, Ce-rich Mischmetal promoted the formation of T-phase while calcium additions resulted in the formation of a ternary Mg Zn Ca compound. Only, manganese additions did not affect the existence of the I-phase present in the ternary alloy. The texture was measured and it was found that calcium addition has a significant effect weakening the extrusion texture.
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corrosion behaviour of mg zn y Mischmetal alloys in phosphate buffer saline solution
Corrosion Science, 2013Co-Authors: P Perez, P Adeva, E Onofre, Sandra Cabeza, I Llorente, J A Del Valle, M C Garciaalonso, M L EscuderoAbstract:Abstract The influence of the processing route and chemical composition in the corrosion behaviour of two Mg–Zn–Y–Mischmetal alloys has been evaluated in phosphate buffer saline solution. The corrosion resistance of the alloy processed by conventional techniques was substantially higher than that found for the same alloy processed from atomised powders. Fine homogeneous distribution of the second-phase particles promoted severe attack due to the enhanced number of galvanic microcells. A higher concentration of zinc and a lower content of rare earth additions improved the corrosion resistance of the alloys due to the lower volume fraction of second-phase particles.
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influence of Mischmetal composition on crystallization and mechanical properties of mg80 ni10 mm10 alloys
Intermetallics, 2009Co-Authors: P Perez, S Gonzalez, G Garces, P AdevaAbstract:The influence of Mischmetal composition, cerium- or lanthanum-rich, on crystallization and mechanical properties of amorphous Mg10Ni10MM10 alloys has been evaluated. The microstructure of the alloys consists of Mg17RE2 matrix (RE denotes a rare earth element) embedding other intermetallic phases whose compositions depend on the nature of Mischmetal addition. Major difference arises from the formation of Ni3RE in the alloy prepared with cerium-Mischmetal instead of the Mg2Ni phase crystallized in the lanthanum-Mischmetal-containing alloy. The mechanical behaviour, however, is very similar independently of the type of Mischmetal added.
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Influence of partial replacement of cerium-rich Mischmetal (CeMM) by yttrium on the crystallization and mechanical properties of amorphous Mg80Ni10CeMM10 alloy
Intermetallics, 2007Co-Authors: P Perez, S Gonzalez, G GarcesAbstract:The influence on the crystallization and mechanical properties of partial replacement of cerium-rich Mischmetal (CeMM) by yttrium in amorphous alloys, whose compositions were close to Mg80Ni10(Y + CeMM)10 (at.%) stoichiometry, has been evaluated. Yttrium addition induces substantial microstructural changes during the crystallization from the amorphous state. The microstructure consisted of a matrix embedding some intermetallic phases, which depend on yttrium and CeMM additions. The matrix is a long period ordered structure for the alloy containing exclusively yttrium whereas the matrix was the intermetallic Mg17RE2 and/or Mg12RE phase for the CeMM-containing alloys. Yttrium improves the mechanical strength of the crystallised alloys once the long period ordered structure is developed.