Effect of cooling rate on solidification parameters and microstructure of Al-7Si-0.3Mg-0.15Fe alloy

Chen, Rui; Shi, Yue; Xu, Qingyan; Liu, Baicheng

doi:10.1016/s1003-6326(14)63236-2

Cited by 105 publications

(53 citation statements)

References 22 publications

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“…The morphology of the solidifed silicon appears to depend upon the solidification speed, defined by the temperature gradient during the solidification and the local chemical composition, specifically when formed in polyhedral and dendritic forms [22,23]. As expected, the microstructure of the as-cast eutectic alloy ( Figure 4(c)) is very much different as Si becomes a majority component.…”

Section: Microstructure Of the Alloysmentioning

confidence: 73%

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Nanostructured magnesium silicide Mg2Si and its electrochemical performance as an anode of a lithium ion battery

Nazer

Denys

Andersen

et al. 2017

Journal of Alloys and Compounds

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Nano-crystalline Mg 2 Si (Mg 67 Si 33 ) and its Si-rich eutectic (Mg 47 Si 53 ) composition were synthesized by hydrogen desorption-recombination process, casting and rapid solidification techniques. The synthesis of Mg 2 Si meets experimental challenges due to a significant difference in the melting temperatures of Mg (650 °C) and Si (1414 °C) and due to easy vaporization of magnesium metal. As cast alloys were obtained by induction melting the precursors, Mg and Si, followed by the casting and water quenching. These alloys were rapidly solidified using a chill block melt spinning which produces ribbons with fine dendritic morphology and a grain size close to 100 nm. Hydrogen desorption-recombination process of MgH 2 -Si mixture resulted in a release of ~ 4.67 wt. % H and formation of Mg 2 Si. The microstructure of the alloys has been studied using Scanning Electron Microscopy and the relationship between microstructure and electrochemical properties as anodes of the lithium ion batteries was characterised. The electrochemical tests indicate that Si rich eutectic electrode shows a higher charge-discharge capacity than the Mg 2 Si intermetallic. Rapidly solidified Mg 2 Si and Mg 2 Si + Si alloys showed the highest initial discharge capacities of 989 mAh/g and 1283 mAh/g, respectively, superior to the alloys prepared by hydrogen desorption-recombination process and casting. The presence of electrolyte additives FEC (5 %) and VC (1 %) resulted in the formation of the stable SEI layer and enhanced the cycling capacity of the electrodes. Electrochemical Impedance Spectroscopy (EIS) was used to characterize the anode electrodes on cycling. A mathematical model for accounting the impedance response was utilised. The EIS response showed an increased overall resistance for the Mg 2 Si eutectic Si-containing alloy electrodes when compared to the electrodes based on a stoichiometric Mg 2 Si. Long-term cycling resulted in increased charge transfer resistance, which slowed down the electrochemical processes at the surface of the electrodes.

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Section: Microstructure Of the Alloysmentioning

confidence: 73%

“…Both mechanisms involve an electrochemically driven alloying processes, which because of a presence of elementary silicon result in a poor cyclic performance due to a high volume expansion of Si of about 400 % (when Li 22 Si 5 is formed [16]). …”

Section: Introductionmentioning

confidence: 99%

Nanostructured magnesium silicide Mg2Si and its electrochemical performance as an anode of a lithium ion battery

Nazer

Denys

Andersen

et al. 2017

Journal of Alloys and Compounds

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“…In order to estimate the average cooling rate (R) reached by the cooling system, the following empirical equations reported in the literature for Al-Si alloys were used 12,13 :…”

Section: Methodsmentioning

confidence: 99%

Effect of Rapid Solidification and Addition of Cu3P on the Mechanical Properties of Hypereutectic Al-Si Alloys

et al. 2016

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The combined processes; rapid solidification, addition of Cu 3 P compound and heat treatments to improve the mechanical properties of the hypereutectic Al-13Si, Al-20Si and Al-20Si-1.5Fe-0.7Mn alloys (in wt. %) was studied. Optical microscopy and scanning electron microscopy were used to characterize the microstructures. The mechanical properties were evaluated by tensile tests. It was found that the cooling rate (20-50°C/s) used to solidify the alloys plus the addition of Cu3P compound favored the formation of fine primary Si and the transformation of the Al/Si eutectic from acicular to semi-transformed morphology. The spheroidization of the Al/Si eutectic after heat treatment caused an increase in the elongation (%) compared with the as-cast alloys. Al-13Si alloy showed the highest UTS and elongation (%) values, reaching values up to 215 MPa and 9.6%, respectively. On the other hand, the Al-20Si-1.5Fe-0.7Mn alloy showed the lowest UTS (180MPa) and elongation (3.4%) values. The formation of the Fe-intermetallic compounds caused a negative effect on the mechanical properties of the Al-20Si-1.5Fe-0.7Mn alloy.

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“…The final number of primary a(Al) grains in the casting depends on the process of nucleation at the beginning of solidification because each nucleus gives rise to one single grain. Consequently, it represents the nucleation potential which depends on the following factors: the type and quantity of the grain refiner addition, the time and liquid metal temperature, slag and furnace atmosphere, molten metal mixing, or the chemical composition of the alloy (Ref [1][2][3][4]. Not all sites found in liquid metal are involved in the nucleation process.…”

Section: Introductionmentioning

confidence: 99%

Effect of Titanium Addition and Cooling Rate on Primary α(Al) Grains and Tensile Properties of Al-Cu Alloy

Górny

Sikora

2015

J. of Materi Eng and Perform

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The research was conducted for castings with 3-25-mm wall thicknesses and using AlTi5B1 master alloy as well as AlTi75 additions. A thermal analysis was performed to determine the real cooling rate and the degree of undercooling (DT a = T a 2 T min , where T a -the equilibrium solidification temperature, T min -the minimum temperature at the beginning of a(Al) solidification) of an Al-Cu alloy. It was shown that the Ti-based grain-refining process does not influence the cooling rate. Metallographic examinations were carried out to determine the primary grains (the number of primary a(Al) grains per unit volume). It was found that the grain count can be properly described by the exponential function of the undercooling for castings processed under various cooling and metallurgical conditions. Combining the cooling rate and the efficient grain refiner increased the tensile ductility by up to 150%.

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Effect of cooling rate on solidification parameters and microstructure of Al-7Si-0.3Mg-0.15Fe alloy

Cited by 105 publications

References 22 publications

Nanostructured magnesium silicide Mg2Si and its electrochemical performance as an anode of a lithium ion battery

Nanostructured magnesium silicide Mg2Si and its electrochemical performance as an anode of a lithium ion battery

Effect of Rapid Solidification and Addition of Cu3P on the Mechanical Properties of Hypereutectic Al-Si Alloys

Effect of Titanium Addition and Cooling Rate on Primary α(Al) Grains and Tensile Properties of Al-Cu Alloy

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