New Insights into the Formation Mechanism of Solid-Liquid Segregation in the Semi-Solid Processing: Macro-Micro Linkage Theory

2020 ◽  
Author(s):  
Wenying Qu ◽  
Daquan Li ◽  
Xiaogang Hu ◽  
Min Luo ◽  
Q. Zhu
Keyword(s):  
Formation Mechanism ◽  
Liquid Segregation ◽  
Semi Solid ◽  
Solid Liquid

Formation Mechanism of Thixotropic Microstructure of AM60 Alloy during Solidification

2014 ◽  
Vol 1030-1032 ◽  
pp. 86-89
Author(s):  
Bo Xing
Keyword(s):  
Formation Mechanism ◽  
Solid Substrate ◽  
Research Field ◽  
Primary Phase ◽  
Solid Particles ◽  
Metallographic Analysis ◽  
Semisolid Slurry ◽  
Dendritic Microstructure ◽  
Quenching Method ◽  
Semi Solid

A research field on semi-solid metal processing is the preparation of semi-solid slurry with non-dendritic microstructure. Nowadays, with the technological innovation of semi-solid slurry preparation, people turn to produce the non-dendritic semisolid microstructure by locally cooling of the alloy melt during solidification. Therefore, it is necessary to investigate the formation mechanism of the non-dendritic microstructure formation because the primary phase undergoes a specially controlled nucleation and growth which distinctly different from the commom solidification. In this paper, the semisolid slurry of AM60 alloy was produced by Self-Inoculation Method (SIM), and the microstructure evolution of primary α-Mg was investigated by water quenching method and metallographic analysis. The results indicate that the semisolid microstructure of AM60 alloy produced by SIM composed of small and globular α-Mg particles, and these grains undergone a coarsing process during quiescent holding. The solid substrate caused by the fusion of solid particles and the dendritic fragments caused by melt flow caused the grain multiplication, and then the grain undergone a steadily growth because of the uniform temperature distribution, resulting in the increase of grains density and a small grain size of the AM60 semisolid slurry.

Effect of RE on Performance of Semi-Solid AlSi7 Alloy

2010 ◽  
Vol 426-427 ◽  
pp. 581-584 ◽  
Author(s):  
Rong Xi Yi ◽  
Shi Kun Xie ◽  
Xiao Qiu Zheng ◽  
Yong Ping Ai
Keyword(s):  
Phase Zone ◽  
Two Phase ◽  
Semi Solid ◽  
Solid Liquid ◽  
Different Content ◽  
Zone Temperature

The semi-solid slurry of AlSi7 alloy was prepared by near-liquids cast processing. The effects of different content of RE on the cast performance and the semi-solid remelting performance in AlSi7 alloy was researched. The results indicated that adding RE will widen the AlSi7 alloy solid-liquid two-phase zone temperature and refine the grains, silicon will obvious metamorphoses. The best amount of RE is about 0.5%. Its semi-solid remelting organization is equilateral globular grains.

Unraveling the Formation Mechanism of Solid–Liquid Electrolyte Interphases on LiPON Thin Films

2019 ◽  
Vol 11 (9) ◽  
pp. 9539-9547 ◽  
Author(s):  
Manuel Weiss ◽  
Beatrix-Kamelia Seidlhofer ◽  
Matthias Geiß ◽  
Clemens Geis ◽  
Martin R. Busche ◽  
...  
Keyword(s):  
Thin Films ◽  
Formation Mechanism ◽  
Liquid Electrolyte ◽  
Solid Liquid

Semi-Solid Casting of Pure Magnesium

2019 ◽  
Vol 285 ◽  
pp. 464-469 ◽  
Author(s):  
Ulyate Andries Curle ◽  
Jeremias D. Wilkins
Keyword(s):  
Temperature Interval ◽  
Liquid Fraction ◽  
Thermodynamic Temperature ◽  
Casting Process ◽  
Pure Magnesium ◽  
Time Interval ◽  
Thermal Arrest ◽  
Solidification Temperature ◽  
Semi Solid ◽  
Solid Liquid

Semi-solid processing works on the principal of a solidification temperature interval of a substance. The substance is heated to a temperature within this interval so that there exists a related solid-liquid fraction ratio. The substance with this phase structure is then shaped by a forging or casting process. It has been stated before that it is impossible to semi-solid process and cast pure metals or eutectic alloys due to their thermodynamic temperature invariance, meaning that there is no temperature interval. It was demonstrated recently that it is possible to semi-solid casting high purity aluminium (Curle UA, Möller H, Wilkins JD. Scripta Materialia 64 (2011) 479-482) and the Al-Si binary eutectic (Curle UA, Möller H, Wilkins JD. Materials Letters 65 (2011) 1469-1472). The working principal is that there exists a time interval during thermal arrest during which solidification takes place with a solid-liquid fraction ratio until all the liquid is consumed upon cooling. The aim with this work is to demonstrate that pure magnesium can also be rheo-high pressure die cast (R-HPDC) with the system developed at the CSIR in South Africa. Magnesium is notoriously difficult to cast due to the thermal properties of magnesium. The metal was poured into a cup, processed for about 6 seconds after which it was HPDC into a plate. The microstructure of the casting consists of a structure that was solid and a structure that was liquid during thermal arrest at the time of casting.

Liquid segregation behavior of semi-solid AZ91 alloy during back extrusion test

2009 ◽  
Vol 477 (1-2) ◽  
pp. 822-827 ◽  
Author(s):  
A. Khosravani ◽  
H. Aashuri ◽  
P. Davami ◽  
A. Narimannezhad ◽  
R. Hadian
Keyword(s):  
Az91 Alloy ◽  
Segregation Behavior ◽  
Liquid Segregation ◽  
Semi Solid

Numerical Simulation of Semi-Solid Die Casting of ZA Alloy Automotive Bushing Based on AnyCasting

2013 ◽  
Vol 411-414 ◽  
pp. 3064-3067 ◽  
Author(s):  
Han Wu Liu ◽  
Zhi Ping Zhang ◽  
Yan Fang Luo ◽  
Li Lu
Keyword(s):  
Heat Dissipation ◽  
Die Casting ◽  
Solidification Process ◽  
Casting Process ◽  
Filling Sequence ◽  
Gas Trapping ◽  
Simulation Results ◽  
Stress And Deformation ◽  
Semi Solid ◽  
Solid Liquid

In order to reduce the wear of parts caused by long-term friction, and to reduce the frequency of parts replacement, ZA alloy with low hardness and good wear resistance is chosen to replace the traditional copper alloy as the material to manufacture automotive bushing, and the semi-solid die casting is used. On this basis, the software AnyCasting is used to simulate and analyze the filling and solidification process, the filling sequence, the variation of temperature field, and the part region where defects are prone to occur in the semi-solid process. The simulation results show that under the parameters set in the simulation process, when casting filling rate reached 90%, the metal started to solidify; since the gate place is easy for heat dissipation, when the temperature of the alloy liquid reached its liquidus temperature 595°C, the phenomenon of solid-liquid phase separation appeared at the gate; the defects such as gas trapping, residual stress and deformation would appear both in the place of first filling and the parting surface; when the preheat temperature of the mold was 150°C-200°C,the alloy liquid possesses liquidity. The simulation results offer certain theoretical instruction to optimize the semi-solid casting process of ZA Alloy automotive bushing manufacturing, as well as reducing or avoiding a variety of quality defects arose in the actual casting process.

Microstructural Evolution of AZ91D-1.5%Er during Semi-Solid Isothermal Treatment

2012 ◽  
Vol 192-193 ◽  
pp. 238-245 ◽  
Author(s):  
Hong Yu Xu ◽  
Ze Sheng Ji ◽  
Zhen Yu Wang
Keyword(s):  
Microstructural Evolution ◽  
Heating Temperature ◽  
Liquid System ◽  
Isothermal Treatment ◽  
Az91d Magnesium Alloy ◽  
Primary Particles ◽  
Recycling Technology ◽  
Paper Chip ◽  
Semi Solid ◽  
Solid Liquid

In this paper, chip recycling technology combined with SIMA method which is called CR-SIMA method was adopted to prepare semi-solid billets. AZ91D magnesium alloy was refined by Er and its microstructural evolution was investigated during semi-solid isothermal treatment. The results show that Er can improve the feature of cast structure and decrease the grain size. Moreover, the γ-Mg17Al12 phase is well refined and disperses in the α-Mg matrix. A semisolid microstructure with small and spheroidal primary particles can be obtained after partially remelting. With increasing heating temperature, the dissolution of eutectic Mg17Al12 phase first took place, resulting in the primary dendritic grains coarsening into interconnected non-dendritic grains. With heating continuously, the residual interdendritic γ-Mg17Al12 at the edges of the primary grains melted in succession and the primary grains separated into small polygon grains. During the semi-solid isothermal treatment, the amount of liquid increased until the solid-liquid system reached its equilibrium state. At the same time, owing to the decreasing of interfacial energy, the grains gradually spheroidized and began to grow with a further increasing of the holding time.

Effect of Isothermal Holding Temperature on Globularization of Primary Solid Phase in Multiplex-Type Slurry Cup

2006 ◽  
Vol 116-117 ◽  
pp. 239-242 ◽  
Author(s):  
Suk Won Kang ◽  
Dock Young Lee ◽  
Ki Bae Kim
Keyword(s):  
Automobile Industry ◽  
Solid Phase ◽  
Isothermal Holding ◽  
Cost Effective ◽  
Al Alloy ◽  
Liquid Region ◽  
Globular Structure ◽  
Semi Solid ◽  
Solid Liquid ◽  
Holding Temperature

In order to produce a high quality and cost effective part in the rheocasting process for an automobile industry it has been important to develop a slurry-on-demand process, which can manufacture the semi-solid slurry having a fine and globular structure of primary solid phase. The morphology of primary solid phase of semi-solid slurry is coarsened and globularized during an isothermal holding process in a solid-liquid region. Accordingly, in this paper, the microstructural evolution of semi-solid slurry during the isothermal holding at a various temperature in solid-liquid region was investigated to examine a coarsening and globularization behavior of primary solid phase. The semi-solid slurry of Al alloy was produced in a slurry maker using a multiplex-type slurry cup that we developed recently. A size of primary solid phase was the finer at the higher holding temperature, but under a constant holding time a roundness degree of primary solid phase was the lower at the lower holding temperature. Also, a coarsening rate of primary solid phase was not considered to be affected significantly by a holding temperature even though a little lower coarsening rate was obtained at the higher holding temperature.

Evolution of the Solidification Microstructure of Rheocast High Purity Aluminium

2012 ◽  
Vol 192-193 ◽  
pp. 109-115 ◽  
Author(s):  
Sarah George ◽  
Robert Knutsen
Keyword(s):  
High Purity ◽  
Liquid Interface ◽  
Cellular Growth ◽  
Solidification Mode ◽  
Purity Aluminium ◽  
High Purity Aluminium ◽  
Semi Solid ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid

High purity aluminium has been successfully rheocast using the CSIR-RCS system combined with high pressure die casting. Analysis of the as-cast microstructure by SEM and EBSD revealed the presence of in-grain substructures. These morphological features show that the overall growth mode of the globular grains during rheocasting is planar, but the presence of these features indicates that the solidification mode is cellular at some stages during the slurry production process. Cellular solidification is associated with unstable growth at the solid-liquid interface and is initiated and exacerbated by solute gradients between the melt and the newly formed solid. This high purity alloy exhibits the same cellular growth, indicating that even minor solute variations have an effect on the stability of the solid-liquid interface and, hence, the mode of solidification during semi-solid rheocasting.

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