Microstructure and properties of rheo-HPDC Al-8Si alloy prepared by air-cooled stirring rod process

Qi, Mingfan; Kang, Yonglin; Zhu, Guangcan

doi:10.1016/s1003-6326(17)60218-8

Cited by 17 publications

(10 citation statements)

References 21 publications

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“…The rheocasting can mainly be classified, according to the solid fraction of semisolid slurry used, into low solid fraction counterpart and high solid fraction counterpart. Among them, rheological casting with a low solid fraction of 5-20% semi-solid slurry was used to produce high-pressure casting of thin-walled shell parts that had a complex shape, as represented by 5G communication radiators [7][8][9]. Whilst, in contrast to a liquid alloy melt, a semi-solid slurry with solid phase fraction of 5-20% had a relatively high viscosity and effectively reduced defects including porosity and shrinkage in the filling process for a low solid fraction rheological casting, consequently improved density of products [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution in semi-solid A356 aluminium alloy treated by ICTE process

Guo

et al. 2023

Materials Science and Technology

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The effects of parameters of a novel internal cooling thermal equilibrium (ICTE) process on microstructure evolution in semi-solid A356 aluminium alloys were investigated. The results indicated that a low predetermined temperature ( T P), a higher mechanical stirring intensity for the thermal equilibrium body (TEB) and a reduced melt mass contributed to obtaining fine grained semi-solid structures. The cooling effect of TEB combined with dendritic remelting fractures of solidified shells formed on surface of TEB at room temperature promoted massive nucleation in alloy melt and contributed to obtaining numerous fine primary solid phases. The ICTE process, which regulated stirring time of TEB, obtained numerous spherical grains and simplified the operational process.

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Section: Introductionmentioning

confidence: 99%

Microstructure evolution in semi-solid A356 aluminium alloy treated by ICTE process

Guo

et al. 2023

Materials Science and Technology

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“…Nowadays, the attention of the researchers is focused on the investigation of the properties of less conventional alloys for SSM processing, like AlSi8 [82], Al5Fe4Cu [83], Al-Zn-Mg-Cu [84], AlZnMg alloys with Sc addition [85], etc., in order to evaluate the advantages in their application as semi-solid manufactured products.…”

Section: Tensile Behaviormentioning

confidence: 99%

Microstructure and Properties of Semi-Solid Aluminum Alloys: A Literature Review

Pola

Tocci

Kapranos

2018

Metals

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Semi-solid processing of aluminum alloys is a well-known manufacturing technique able to combine high production rates with parts quality, resulting in high performance and reasonable component costs. The advantages offered by semi-solid processing are due to the shear thinning behavior of the thixotropic slurries during the mold filling. This is related to the microstructure of these slurries consisting of solid, nondendritic, near-globular primary particles surrounded by a liquid matrix. This paper presents a review on the formation of this nondendritic microstructure, reports on the different proposed mechanisms that might be responsible, and illustrates the relationship between microstructure and properties, in particular, tensility, fatigue, wear, and corrosion resistance.fraction. Unfortunately, all these tend to increase the production costs [8], even though recent investigations have shown that SSM processing is only slightly more expensive than conventional die-casting and cheaper than some other competing foundry processes [9].Since its development in the early 1970s at MIT [10], much research has been performed worldwide, aimed mainly at developing new and alternative routes of feedstock production for different alloys suitable for SSM processing. At present, there are a number of different techniques used to produce semi-solid castings, differentiated by the percentage of liquid/solid fraction they employ and the way they produce the alloy in the semi-solid state. SSM methods can be divided in two main categories according to their processing route, known as rheocasting and thixocasting [11]. In rheocasting, the semi-solid slurry is prepared in situ from the liquid state down to a certain percentage of solid fraction (usually between 10 and 30% [12]), and then directly transferred into the shot sleeve for being injected into the die. In thixocasting, a billet, characterized by an almost globular or rosette-like microstructure developed through some specific route, is reheated in the mushy zone (semi-solid region) to an appropriately chosen solid fraction (usually between 50% and 60% [13]), placed in a modified shot sleeve and finally injected into the die [14]. Another classification methodology distinguishes the SSM methods according to the initial step used for obtaining the semi-solid feedstock, i.e., from the liquid state, by controlled solidification or from the solid state, via heavy plastic deformation and recrystallization [11].Some of the most common routes for feedstock material preparation are: mechanical stirring, such as the SSR [15,16] or GISS [17] processes, electromagnetic stirring (EMS or MHD) [18,19], ultrasonic stirring (UTS) [20,21], New Rheocasting (NRC or UBE) [22,23], cooling slope [24], twin screw [25], Rheometal [26], liquid mixing method [27], SEED [28], thermomechanical [29], and SIMA [14,30].A number of interesting reviews about the different technologies available for obtaining nondendritic slurries can be found in the literature [11,13,14,[31][32][33]. Nevertheless, indep...

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“…Compared with traditional liquid forming, when the high-viscosity melt moves forward smoothly during the filling process of semi-solid die-casting, the gas in the cavity is discharged smoothly and entrainment does not easily occur [2]. Due to the existence of solid phase, the shrinkage produced during the solidification process is small, and it is not easy to produce hole defects [3], so that the semi-solid forming products have high compactness and can be heat treated to improve the mechanical properties again [4,5]. Initially, semi-solid processing techniques, such as mechanical stirring method [5,6] and electromagnetic stirring method [7,8], were mainly used for experimental research with few industrial applications.…”

Section: Introductionmentioning

confidence: 99%

“…Kang et al [2] studied the semi-solid structure of 7075 aluminum alloy and found that increasing the stirring speed and prolonging the stirring time within a certain range was conducive to the refinement and spheroidization of primary grains. Qi [3] studied the effect of gas flow on Al-8Si aluminum alloy slurry and believed that with the increase of gas flow, the critical nucleation energy required to form grains decreased, leading to an increased nucleation rate, which was beneficial to obtain more fine grains. Gao et al [19] used orthogonal experiments to study the effects of gas flow, stirring temperature, stirring time and sampling temperature on the semi-solid microstructure, and found that stirring time and stirring temperature were the main factors affecting the microstructure, with a reliability of 95%.…”

Section: Introductionmentioning

confidence: 99%

Effects of Process Parameters on Microstructure and Mechanical Properties of Semi-Solid Al-7Si-0.5Mg Aluminum Alloy by Gas Induced Semi-Solid Process

Xiang

et al. 2022

Metals

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Al-7Si-0.5Mg aluminum alloy semi-solid slurry with good spherical grains was prepared by gas induced semi-solid process (GISS) and the effects of both holding time and medium alloy addition on the microstructure of the semi-solid slurry were investigated. These two parameters have a great influence on the solid fraction, the size and the sphericity of the grains. With holding time increased from 85 s to 270 s, the solid phase fraction of the semi-solid slurry decreased from ~0.77 to ~0.67, the average grain size increased from ~95 μm to ~225 μm and the average shape factor decreased from ~0.80 to ~0.33. When medium alloy addition varied in the range of 0.5–2.0 wt%, a better slurry microstructure was obtained at about 1.5 wt%. Compared with the conventional liquid die-casting, the semi-solid die-casting improved the mechanical properties of tensile bars; yield strength, tensile strength and elongation of tensile bars reached ~240 MPa, ~307 MPa and ~8.8% after heat treatment, respectively. In conclusion, GISS process can prepare the semi-solid slurry with uniform and round microstructure, and the semi-solid die-casting can improve mechanical properties of Al-7Si-0.5Mg aluminum alloy.

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Microstructure and properties of rheo-HPDC Al-8Si alloy prepared by air-cooled stirring rod process

Cited by 17 publications

References 21 publications

Microstructure evolution in semi-solid A356 aluminium alloy treated by ICTE process

Microstructure evolution in semi-solid A356 aluminium alloy treated by ICTE process

Microstructure and Properties of Semi-Solid Aluminum Alloys: A Literature Review

Effects of Process Parameters on Microstructure and Mechanical Properties of Semi-Solid Al-7Si-0.5Mg Aluminum Alloy by Gas Induced Semi-Solid Process

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