Strontium modification and formation of cubic primary Mg2Si crystals in Mg2Si/Al composite

Qin, Qun; Zhao, Yi; Liu, C.; Peng, Cong; Zhou, W.

doi:10.1016/j.jallcom.2006.12.074

Cited by 116 publications

(52 citation statements)

References 13 publications

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“…Mg 2 Si because it is light, and has a high melting point and elastic modulus [13] . According to the Al-Mg 2 Si phase diagram, Mg 2 Si reinforcements can be produced from molten Al during solidification as follows [14] :…”

Section: One Of the Suitable Reinforcements For The Amcs Ismentioning

confidence: 99%

Effect of reinforcement amount, mold temperature, superheat, and mold thickness on fluidity of in-situ Al-Mg2Si composites

Barenji

2018

China Foundry

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A luminum matrix composites (AMCs) are frequently used in different industries. This is due to the fact that AMCs are light and have good specific strength and stiffness. Thus, these new materials can be an appropriate option for replacement of the heavy alloys such as steels [1][2][3][4][5][6][7][8] .AMCs can be produced using casting methods such as ex-situ and in-situ processes. In the ex-situ process, reinforcement particles are added to the molten metal, usually accompanied by a stirring action. In the insitu process, the reinforcements of secondary phase are produced either in molten metal or in solidification. Therefore, the wetting problem of the secondary phases is solved by the in-situ method, and hence the distribution of the reinforcements is more uniform than that of the ex-situ method. This advantage of the in-situ Abstract: In the present study, the effects of mold temperature, superheat, mold thickness, and Mg 2 Si amount on the fluidity of the Al-Mg 2 Si as-cast in-situ composites were investigated using the mathematical models. Composites with different amounts of Mg 2 Si were fabricated, and the fluidity and microstructure of each were then analyzed. For this purpose, the experiments were designed using a central composite rotatable design, and the relationship between parameters and fluidity were developed using the response surface method. In addition, optical and scanning electron microscopes were used for microstructural observation. The ANOVA shows that the mathematical models can predict the fluidity accurately. The results show that by increasing the mold temperature from 25 °C to 200 °C, superheat from 50 °C to 250 °C, and thickness from 3 mm to 12 mm, the fluidity of the composites decreases, where the mold thickness is more effective than other factors. In addition, the higher amounts of Mg 2 Si in the range from 15wt.% to 25wt.% lead to the lower fluidity of the composites. For example, when the mold temperature, superheat, and thickness are respectively 100 °C, 150 °C, and 7 mm, the fluidity length is changed in the range of 11.9 cm to 15.3 cm. By increasing the amount of Mg 2 Si, the morphology of the primary Mg 2 Si becomes irregular and the size of primary Mg 2 Si is increased. Moreover, the change of solidification mode from skin to pasty mode is the most noticeable microstructural effect on the fluidity.

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Section: One Of the Suitable Reinforcements For The Amcs Ismentioning

confidence: 99%

Effect of reinforcement amount, mold temperature, superheat, and mold thickness on fluidity of in-situ Al-Mg2Si composites

Barenji

2018

China Foundry

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“…Mg-Si alloys can be divided into two groups: hypoeutectic (below 1.45 at.% Si) and hypereutectic (above 1.45 at.% Si). Unfortunately, the as-cast hypereutectic alloys have a low mechanical properties due to the presence of primary Mg2Si compound which forms the large particles in the matrix [9][10][11][12][13][14]. In order to improve the mechanical properties the modified treatment can be used, however, the improvement of mechanical properties after modification is not impressive.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Aluminum on the Microstructure and Hardness of Mg-5Si-7Sn Alloy

Rzychoń¹,

Dybowski²

2016

Archives of Metallurgy and Materials

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Magnesium alloys due the low density and good mechanical properties are mainly used in the automotive and aerospace industry. In recent years, magnesium alloys are extensively developed for use in high temperatures (above 120°C). Among these alloys, magnesium alloys containing tin and silicon have large possibilities of application due to the formation of thermally stable intermetallic Mg2Sn and Mg2Si. In this paper the influence of aluminum and heat treatment on the on the microstructure and hardness of Mg-7Sn-5Si alloy is reported. It was found that the microstructure of Mg-7Sn-5Si alloy consist of α-Mg solid solution, Mg2Sn and Mg2Si compounds. Addition of 2 wt% of Al to Mg-7Sn-5Si alloy causes the formation of Al2Sn phase. Moreover, Al dissolves in the α-Mg solid solution. The solution heat-treatment of tested alloys at 500°C for 24 h causes the dissolve the Mg2Sn phase in the α-Mg matrix and spheroidization of Mg2Si compound. The Mg2Si primary crystals are stable at solution temperature. After ageing treatment the precipitation process of equilibrium Mg2Sn phase was found in both alloys. The addition of aluminum has a positive effect on the hardness of Mg-7Sn-5Si alloy. In case of Mg-5Si-7Sn-2Al alloy the highest hardness was obtained for sample aged for 148 h at 250°C (88 HV2), while in case of Al-free alloy the highest hardness is 70 HV for material aged for 148 h at 250°C.

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“…Therefore, composites with a predominantly coarse primary Mg 2 Si crystal must be modi ed to ensure adequate mechanical strength and ductility 5) . Recently, it was reported that modi cation of microstructure has been developed through common gravity casting by additions of mischmetal 7) , strontium 8,9) or phosphorus 5,10) . After modi cation, the morphology of primary Mg 2 Si phase changed from dendritic or irregular to polygonal or quadrangular shape.…”

Section: Introductionmentioning

confidence: 99%

Effects of Sr+Ce on Microstructure and Abrasive Resistance of <i>In-Situ</i> Mg<sub>2</sub>Si/Al-Si-Cu Composites

Qin

Li²

2016

Mater. Trans.

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In the present study, the modi cation effect of Sr+Ce in Mg 2 Si/Al-Si-Cu composites was investigated for controlling both the microstructure and mechanical properties. Furthermore, the hardness and the abrasive resistance after modi cation were also studied. The results show that when the composites were modi ed by 0.40 mass% Ce, the morphology of the primary Mg 2 Si phase changes to a polygonal morphology with a size of 15 μm. However, in those with a 0.40 mass% Ce and 0.05 mass% Sr addition, the morphology changes to an irregular and equiaxed shape, and the size increases to 50 μm. Furthermore, in the 0.40 mass% Ce and 0.10 mass% Sr addition, the primary Mg 2 Si morphology transforms to a rectangular trapezoid, or T shape, with sizes measuring 70 μm. Additionally, in the 1.00 mass% Ce and 0.05 mass% Sr, and the 1.00 mass% Ce and 0.10 mass% Sr addition, the primary Mg 2 Si morphologies become either polygonal or irregular shaped, respectively. The eutectic phases change shows that, with the addition of Ce or Sr, the eutectic phases exist in the form of the binary eutectic of Al+Mg 2 Si or the ternary eutectic of Al+Mg 2 Si+Si. The hardness test illustrates that the hardness of the 1.00 mass% Ce and 0.05 mass% Sr and the 0.40 mass% Ce and 0.05 mass% Sr, modi ed composites are higher than the unmodi ed composites. The abrasive resistance data shows that modi ed composites with the 1.00 mass% Ce and 0.05 mass% Sr are higher than that of the modi ed and unmodi ed composites with a 0.40 mass% Ce and 0.05 mass% Sr. The abrasive resistance agrees with the hardness test results, and this demonstrates that the Sr+Ce addition can change the microstructure and enhance the mechanical properties of the material.

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Strontium modification and formation of cubic primary Mg2Si crystals in Mg2Si/Al composite

Cited by 116 publications

References 13 publications

Effect of reinforcement amount, mold temperature, superheat, and mold thickness on fluidity of in-situ Al-Mg2Si composites

Effect of reinforcement amount, mold temperature, superheat, and mold thickness on fluidity of in-situ Al-Mg2Si composites

The Influence of Aluminum on the Microstructure and Hardness of Mg-5Si-7Sn Alloy

Effects of Sr+Ce on Microstructure and Abrasive Resistance of <i>In-Situ</i> Mg<sub>2</sub>Si/Al-Si-Cu Composites

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