Magnesium Matrix Composite Foams—Density, Mechanical Properties, and Applications

Gupta, Nïkhil; Luong, Dung D.; Cho, Kyu

doi:10.3390/met2030238

Cited by 81 publications

(67 citation statements)

References 52 publications

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“…On one hand, the viscosity at edge of billet is higher than the center due to cooling water in crystallizer, leading to the increase of attenuation coefficient (α), so acoustic intensity decreases heavily at the edge of the liquid cave. On the other hand, according to the results of numerical simulation (seen in Figure 8), the average acoustic pressure (p) at edge and 1/2R of the liquid cave is lower than center, meaning the sound intensity (I) is lower at edge and 1/2R of liquid cave according to Equation (4). Thus, the grain refinement effect is weakened in edge and 1/2R.…”

Section: Microstructure Refinement By Different Ultrasonic Treatmentsmentioning

confidence: 94%

Variable-Frequency Ultrasonic Treatment on Microstructure and Mechanical Properties of ZK60 Alloy during Large Diameter Semi-Continuous Casting

Chen

Wang

et al. 2017

Metals

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Traditional fixed-frequency ultrasonic technology and a variable-frequency ultrasonic technology were applied to refine the as-cast microstructure and improve the mechanical properties of a ZK60 (Mg-Zn-Zr) alloy during large diameter semi-continuous casting. The acoustic field propagation was obtained by numerical simulation. The microstructure of the as-cast samples was characterized by optical and scanning electron microscopy. The variable-frequency ultrasonic technology shows its outstanding ability in grain refinement compared with traditional fixed-ultrasonic technology. The variable-frequency acoustic field promoted the formation of small α-Mg globular grains and changed the distribution and morphology of β-phases throughout the castings. Ultimate tensile strength and elongation are increased to 280 MPa and 8.9%, respectively, which are 19.1% and 45.9% higher than the values obtained from billets without ultrasonic treatment and are 11.6% and 18.7% higher than fixed-frequency ultrasound treated billets. Different refinement efficiencies appear in different districts of billets attributed to the sound attenuation in melt. The variable-frequency acoustic field improves the refinement effect by enhancing cavitation-enhanced heterogeneous nucleation and dendrite fragmentation effects.

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Section: Microstructure Refinement By Different Ultrasonic Treatmentsmentioning

confidence: 94%

Variable-Frequency Ultrasonic Treatment on Microstructure and Mechanical Properties of ZK60 Alloy during Large Diameter Semi-Continuous Casting

Chen

Wang

et al. 2017

Metals

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“…En la indústria automotriz, el uso de espumas ultralivianas de magnesio (Mg) o sus aleaciones, con una densidad entre 0,5 -1,5 g/cm 3 , permitirían cumplir con dos requisitos: disminución de peso (mayor eficiencia y menor polución) y absorción de energía de impacto (menores daños a los pasajeros del vehículo) [8,9,10].…”

Section: Introductionunclassified

Espuma ultraliviana de Mg a partir de viruta reciclada

et al. 2018

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RESUMENCientos de personas en el mundo mueren o quedan seriamente dañadas a causa de colisiones en accidentes de tránsito, debido a la energía que se transmite a los ocupantes del auto por el impacto. Para minimizar esta energía, es necesario disiparla mediante absorbedores. En años recientes, se empezaron a considerar las espumas metálicas como absorbedores de energía. Las espumas metálicas son materiales estructurales relativamente desconocidos, pero con un enorme potencial para aplicaciones donde el bajo peso combinado con alta rigidez son de principal interés. El uso de espumas ultra-livianas de magnesio (Mg) o sus aleaciones, permitirían cumplir con dos requisitos: disminución de peso (mayor eficiencia y menor polución) y absorción de energía de impacto (menores daños a los pasajeros del vehículo).El mecanizado de cajas de cambio de aleación de magnesio AZ91D en la indústria autopartista, genera una gran cantidad de viruta contaminada con aceites. En este trabajo se usa la metalurgia de polvos como método para la recuperación de la viruta de aleación AZ91D. Se estudiaron las condiciones pulvimetalúrgicas para la obtención de una espuma a partir de viruta y separador (bicarbonato de amonio). El material obtenido se caracterizó físicamente determinando la densidad de la espuma y mecánicamente mediante ensayos de compresión, obteniendo valores de energía absorbida y energía absorbida específica, que son los datos que caracterizan una espuma. Finalmente, se lo caracterizó metalográficamente utilizando microscopía óptica y electrónica confocal. Se probaron distintos porcentajes de porosidad (50 y 70%). La energía absorbida por unidad de masa (J/g) de la espuma con 50 % de porosidad resultó ser mayor al doble de la absorbida por el magnesio sinterizado sin separador Palabras clave: Espumas metálicas, absorbedores, energía. ABSTRACTHundreds of people worldwide die or are severely maimed in collisions during traffic accidents, due to the energy transmitted to the passengers on impact. A dissipation of said energy is necessary to minimize it's effects, which can be achieved through absorbers. In recent years, metallic foams have started to be considered as energy absorbers. Metallic foams are relatively unknown structural materials, but with huge potential for applications where low weight but high rigidity are of primary interest. The use of ultralight magnesium (Mg) or magnesium alloy foams has two main advantages: less weight (more vehicle efficiency and less pollution) and impact energy absorption (less harm to passengers on board the vehicle).The machining of gearboxes made out of AZ91D magnesium alloy, generates large amounts of oilcontaminated metallic shavings. In this work, powder metallurgy is used as a recycling method of the AZ91 alloy. There were studied the conditions needed for obtaining metallic foam from recycled shavings of AZ91 and spacer (ammonium bicarbonate). The final product was characterized physically by determination of the foam's density. Also, compression tests were done to obtain values...

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“…Rohatgi et al [18] obtained by the die casting technique a composite based on the AZ91 magnesium alloy matrix with cenospheres. Analogical material was fabricated by the stir casting method by Huang et al, [19] Lu et al, [20] and Gupta et al [21] A composite based on the AZ91 alloy with cenospheres was obtained by the pressure infiltration process by Liu et al [22] Daoud et al [23] investigated a composite fabricated on the base of the ZC63 magnesium alloy by the stir casting technique. The main problem during the fabrication of cast metal matrix composites with cenospheres is the destruction of their walls due to mechanical damage or chemical reaction with the liquid alloy matrix.…”

Section: Introductionmentioning

confidence: 99%

The Role of Ni-P Coating Structure on Fly Ash Cenospheres in the Formation of Magnesium Matrix Composites

Braszczyńska-Malik

Kamieniak

2017

Metall Mater Trans A

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The role of the Ni-P coating structure on fly ash cenospheres in the fabrication of magnesium matrix composites has been investigated. Two composites based on AZ91 commercial magnesium alloys with hollow aluminosilicate cenospheres were fabricated by the negative pressure infiltration technique. Two kinds of cenospheres (i.e., as Ni-P coated and after heat treatment) were used in order to determine the influence of the Ni-P coating structure on creating interfaces between the components. Microstructure analyses were carried out by light microscopy, atomic force microscopy, XRD, scanning, and transmission electron microscopy. Al 3 Ni 2 and Mg 2 Ni intermetallic phases at the component interfaces were formed in the composite with as-received Ni-P-coated cenospheres. After heat treatment of the Ni-P-coated cenospheres, NiO was created outside the external layer of the Ni-P coatings and this oxide remained stable at the component interfaces during composite fabrication. In both cases, the Ni-P coating prevented the reaction between the cenosphere walls and the magnesium matrix alloy, which contributed to obtaining intact cenospheres, unfilled by the matrix alloy.

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Magnesium Matrix Composite Foams—Density, Mechanical Properties, and Applications

Cited by 81 publications

References 52 publications

Variable-Frequency Ultrasonic Treatment on Microstructure and Mechanical Properties of ZK60 Alloy during Large Diameter Semi-Continuous Casting

Variable-Frequency Ultrasonic Treatment on Microstructure and Mechanical Properties of ZK60 Alloy during Large Diameter Semi-Continuous Casting

Espuma ultraliviana de Mg a partir de viruta reciclada

The Role of Ni-P Coating Structure on Fly Ash Cenospheres in the Formation of Magnesium Matrix Composites

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