Microstructure Evolution of Conventional and Semi-Solid A356 Alloy with Addition of Strontium

2015 ◽  
Vol 1087 ◽  
pp. 488-492
Author(s):  
Yuan Sieng Seo ◽  
Laila Masrur Mohd Nasir ◽  
Hussain Zuhailawati ◽  
Anasyida Abu Seman
Keyword(s):  
Phase Analysis ◽  
Eutectic Alloy ◽  
Cast Alloy ◽  
Dendritic Structure ◽  
A356 Alloy ◽  
Melting Furnace ◽  
Eutectic Structure ◽  
Globular Structure ◽  
Semi Solid ◽  
Steel Mould

In this study, modification of aluminium silicon eutectic alloy by grain modifier, strontium was investigated on conventional and slope cast A356 alloy. A356 alloy with addition of 0 to 0.97 wt.% Sr was prepared by conventional and slope casting in melting furnace. The molten metal of A356 alloy was casted into steel mould. Microstructure was observed using SEM. Phase analysis was done using XRD. Microhardness was conducted using Vicker microhardness. Microstructure of conventional cast displayed dendritic structure whereas slope cast displayed globular structure. Addition of Sr refined eutectic structure in both conventional and slope cast alloy. Phase analysis revealed the presence of Al2Sr phase in conventional cast Al-6Si-0.97Sr. Microhardness of the conventional cast alloy decreased with increasing of Sr up to 0.97 wt.%.

Microstructure Evolution of Conventional and Semi-Solid Cast of A356 Aluminium Alloy with Addition of Inoculant

2015 ◽  
Vol 819 ◽  
pp. 25-30 ◽  
Author(s):  
M.N. Laila Masrur ◽  
M. Syukron ◽  
H. Zuhailawati ◽  
A.S. Anasyida
Keyword(s):  
Aluminium Alloy ◽  
Dendritic Structure ◽  
A356 Alloy ◽  
Optical Microscope ◽  
Globular Structure ◽  
Average Grain Size ◽  
Semi Solid ◽  
Vicker’S Microhardness ◽  
Steel Mould ◽  
A356 Aluminium Alloy

This paper investigated the effect of inoculant, Al-5Ti-1B in conventional and semi-solid casting A356 aluminium alloy. A356 aluminium alloy was melted at 850 oC and poured at 680 °C directly into the steel mould and on the inclined slope into steel mould. Inoculant was added in various percentages of 1 wt.%, 2 wt.%, 3 wt.% and 3.5 wt.% in A356 aluminium alloy melt. Microstructure and microhardness were characterized using optical microscope and Vicker’s microhardness tester. The addition of master alloy up 3.5 wt.% Al-5Ti-1B in conventional casting refined dendritic structure with average grain size of 33.41 μm. The microstructures of semi-solid A356 aluminium alloy with addition of Al-5Ti-1B consist of equiaxed structure of α-Al. Further addition of Al-5Ti-1B refined the globular structure of α-Al. The higher hardness was achieved for A356 alloy prepared using semi-solid with addition of 3.5 wt.% of Al-5Ti-1B.

Study of Microstructural Evolution and Phase’s Morphology after Partial Remelting in A356 Alloy

2008 ◽  
Vol 141-143 ◽  
pp. 367-372 ◽  
Author(s):  
A. Mahdavi ◽  
M. Bigdeli ◽  
M. Hajian Heidary ◽  
F. Khomamizadeh
Keyword(s):  
Dendritic Structure ◽  
A356 Alloy ◽  
Intermetallic Phases ◽  
Effective Parameters ◽  
Dendritic Microstructure ◽  
Globular Structure ◽  
Needle Morphology ◽  
Sima Process ◽  
Semi Solid ◽  
Globular Form

In this work, effective parameters of SIMA process to obtain non dendritic microstructure in A356 alloy were investigated. In addition, the effect of SIMA process on the evolution of morphology of silicon and intermetallic phases in this alloy was studied. Microstructure images obtained from optical microscopy and SEM observation showed that increase in plastic work up to 40% and then holding of samples in the semi solid state at temperature of 580oC, causes that primary dendritic structure changes to non dendritic, fine and globular structure, but optimum reheating time completely depended on initial thickness of samples. If all parameters of SIMA process are the same, the grain boundaries of thinner samples begin to wet and following globalization will be completed in shorter reheating time rather than thicker ones. Moreover, it was found that the intermetallic phases lost their angular or needle morphology and gradually changed to rounded morphology and even to globular form. Also the optimum reheating time thoroughly depends on primary casting microstructure as the finer casting microstructure begin to globalize faster than thicker one under more little stains.

Effect of Ni Coating on Hydrogenation Kinetics in Pure Mg and Mg-Mg2Ni Eutectic Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 865-868 ◽  
Author(s):  
Masaaki Kusumoto ◽  
Hideyuki Saitoh
Keyword(s):  
Surface Modification ◽  
Eutectic Alloy ◽  
Catalytic Effect ◽  
Cast Alloy ◽  
Eutectic Structure ◽  
Hybridization Method ◽  
Alloy Specimen ◽  
Heat Treated ◽  
Hydrogenation Kinetics ◽  
Kinetics Of

We have applied hybridization method to the surface modification by Ni coating on powder specimens of pure Mg and Mg-Mg2Ni eutectic alloy, and investigated the effect of the Ni coating on the hydrogenation kinetics in them. The hydrogenation kinetics at 350 degree C is greatly increased by the Ni coating for both the pure Mg and Mg-Mg2Ni eutectic alloy specimens. Thus, it is confirmed that the surface modification by the hybridization method is considerably effective to improve the hydrogenation kinetics in them. This improvement is thought to be a catalytic effect of the coated Ni. The hydrogenation kinetics of the Mg-Mg2Ni alloy specimen heat-treated at 470 degree C has increased compared with that of the as-cast alloy specimen. It is also confirmed that hydrogenation kinetics improves by the heat treatment to grow the eutectic structure consisted of Mg2Ni phase and Mg phase.

The Effect of Initial Microstructure of A356 Alloys on the Mechanical Behavior in the Semisolid State

2006 ◽  
Vol 116-117 ◽  
pp. 449-452 ◽  
Author(s):  
Zhi Liang Ning ◽  
H. Wang ◽  
Jian Fei Sun
Keyword(s):  
Strain Rate ◽  
Dendritic Structure ◽  
A356 Alloy ◽  
Rate Sensitivity ◽  
Process Conditions ◽  
Semisolid State ◽  
Globular Structure ◽  
Initial Microstructure ◽  
Wide Range ◽  
Semisolid Casting

The quality of semisolid casting largely depends on the formability of the semisolid feedstock. Despite of the semisolid casting process conditions, the initial microstructure of the feedstock plays a significant role in determining the metal formability under the semisolid state. In this study, the effect of initial microstructure of A356 alloy on the mechanical forming response in its semisolid state was investigated. A wide range of the initial microstructures varied from a very coarse dendritic structure to a fine globular structure were produced in A356 alloy using the Controlled Nucleation Method, particularly by controlling pouring temperature during solidification. Cylindrical specimens with 12 mm in diameter and 10 mm in height were compressed to a height reduction of 8 mm at constant strain rates from 1.3910-1 /s to 1.3910-3 /s. Strain rate jump tests were also carried out in order to evaluate the strain rate sensitivity at high fraction solid of 0.9. The materials produced with a low superheat exhibit a fine globular structure. They showed a very low compression stress in the semisolid state compared with the materials poured at high temperatures, which have coarse and dendritic structure.

scholarly journals Microstructure and Mechanical Properties of Ultrafine Quaternary Al-Cu-Si-Mg Eutectic Alloy

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 7
Author(s):  
Qing Cai ◽  
Brian Cantor ◽  
Vivian S. Tong ◽  
Feng Wang ◽  
Chamini L. Mendis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Eutectic Alloy ◽  
Cast Alloy ◽  
Eutectic Reaction ◽  
High Strength ◽  
Eutectic Structure ◽  
Eutectic Cell ◽  
Orientation Relationships ◽  
Arc Melting ◽  
Alloy Microstructure

The microstructure evolution and mechanical properties of quaternary Al-Cu-Si-Mg eutectic alloy prepared via arc melting and suction casting were studied. This alloy exhibits a single endothermic DSC peak with a melting temperature of 509 °C upon heating, suggesting a eutectic reaction. The cast alloy microstructure consisted of four phases, α-Al, Al2Cu (), Si and Al4Cu2Mg8Si7 (Q), in the eutectic cells and also in the nano-scale anomalous eutectic in the intercellular regions. The eutectic cells show different morphologies in different parts of the sample. Well-defined orientation relationships between the α-Al, Al2Cu, and Q phases were found in the eutectic cell centres, while decoupled growth of Q phase occurred at the cell boundaries. The bimodal microstructure exhibits excellent compressive mechanical properties, including a yield strength of 835 ± 35 MPa, a fracture strength of ~1 GPa and a compressive fracture strain of 4.7 ± 1.1%. The high strength is attributed to a combination of a refined eutectic structure and strengthening from multiple hard phases.

Characterization of Globular Microstructure in NMS Processed Aluminum A356 Alloy: The Role of Casting Size

2011 ◽  
Vol 264-265 ◽  
pp. 1868-1877 ◽  
Author(s):  
Farshad Akhlaghi ◽  
Amir H.S. Farhood
Keyword(s):  
A356 Alloy ◽  
Systematic Investigation ◽  
Globular Structure ◽  
Near Net Shape ◽  
Size And Morphology ◽  
Semi Solid ◽  
Aluminum A356 Alloy ◽  
Processing Steps

Semi-solid processing (SSP) technology, due to its ability to provide near-net-shape components with properties far exceeding those of other casting technologies is considered as an alternative for forgings and investment castings. Conventional semi-solid forming, involving the use of heated billets, melt stirring or using cooling slopes require many processing steps and supplementary equipments. This article describes Narrow Melt Stream (NMS), as an alternative process for semi-solid processing of aluminum alloys that eliminates capital cost expenditures, reduces the number of steps required, and hence reduces the costs of making components with a globular structure. However, the applicability of this technique in producing globular structures in the large molds has not been explored. In the present study the results of a systematic investigation on the effects of mold size on the size and morphology of the globular structures formed by NMS processing of Al 356 alloy is reported. For this purpose, five different series of molds were employed. Each series consisted of three molds with identical volumes but different casting moduluses. By using these molds, the effects of casting modulus at constant casting size as well as the effect of casting volume on the size and shape factor of the globular structures in aluminum A356 samples prepared by NMS technique is reported.

Research on the Microstructure and Microhardness of 9Cr18 Semi-Solid Billet

2015 ◽  
Vol 817 ◽  
pp. 278-282 ◽  
Author(s):  
Yong Jin Wang ◽  
Ren Bo Song ◽  
Ya Ping Li ◽  
Ruo Ling Bi
Keyword(s):  
Energy Dispersive Spectrometer ◽  
Eutectic Structure ◽  
X Ray Diffraction ◽  
Graded Materials ◽  
Primary Austenite ◽  
Secondary Austenite ◽  
Austenite Grains ◽  
Semi Solid ◽  
Sloping Plate ◽  
Eutectic Area

Formed in the semi-solid state, materials can obtain unconventional microstructures and properties compared with traditional method. In this paper, semi-solid billet of 9Cr18 steel was obtained through a wavelike sloping plate. Microstructure analysis of the semi-solid billet was conducted through scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). X-ray diffraction (XRD) test and microhardness test were also used to analyze the properties. The results showed that the structure of 9Cr18 semi-solid billet contained globular primary austenite and secondary austenite-Cr7C3 eutectic. Globular primary austenite grains were first formed during partial solidification in the sloping plate, and then the rest liquid metal formed secondary austenite and Cr7C3 eutectic structure surrounding the primary grains. Cr atoms had a concentration in the rest liquid side, which along with C atoms contributed to the formation of the Cr7C3 carbide. Hardness in the primary solid grain area and the eutectic area was about 330 HV and 650 HV, respectively. These specific properties were important for subsequent thixoforming of the functional graded materials.

Microstructure of Sodium or Potassium Added Mg-Ni Eutectic Alloy

2014 ◽  
Vol 353 ◽  
pp. 228-232
Author(s):  
Hideyuki Saitoh ◽  
Y. Shiraishi
Keyword(s):  
Eutectic Alloy ◽  
Lamellar Spacing ◽  
Eutectic Structure ◽  
Water Quenching ◽  
Rapid Cooling ◽  
Cooling Speed ◽  
Sodium And Potassium ◽  
Refinement Effect ◽  
Potassium Addition

The microstructure of sodium or potassium added Mg-23.5 mass%Ni eutectic alloy was observed and the effect of sodium and potassium addition on the eutectic structure was investigated. All alloys showed the eutectic structure which composed of Mg phase and Mg2Ni phase, and no evidence of the sodium or potassium precipitation occurred. For the sodium added and furnace cooled alloy, the lamellar spacing in the eutectic structure became a little narrow and the Mg2Ni phase tends to become fragmentary as the amount of sodium increases. The sodium addition has a little effect for the refinement of the eutectic structure. For the potassium added and furnace cooled alloy, the lamellar spacing of the eutectic structure became clearly narrow even by the 0.1 mass% potassium additions. The morphology drastically varied in more than 0.5 mass% potassium added specimens, that is, the refinement and fragmentation of the Mg2Ni phase occurred. The potassium addition has a large effect for the refinement and the fragmentation of the Mg2Ni phase in the eutectic structure. For the water quenched specimens, the eutectic structure was extremely fine and globular shape with and without the additive element. The refinement effect by the water quenching is remarkably high even as the non-added specimen. The effect of sodium and potassium addition on the refinement of eutectic structure is not clear in the case of the rapid cooling speed during solidification.

A Control of Microstructure of A356 Alloy by Sequential Semi-Solid Process

2008 ◽  
pp. 569-573
Author(s):  
Sung Chul Lim ◽  
Hai Joong Lee ◽  
Jang Won Kang ◽  
Sang Kil Lee ◽  
Kyung Hoon Kim ◽  
...  
Keyword(s):  
A356 Alloy ◽  
Semi Solid

Die Design for Main Bearing Cap of Engine Block Based Semi-Solid Die Casting Process and the Comparison Analysis with Squeeze Casting Process

2019 ◽  
Vol 285 ◽  
pp. 429-435 ◽  
Author(s):  
Song Chen ◽  
Da Quan Li ◽  
Fan Zhang ◽  
Min Luo ◽  
Xiao Kang Liang ◽  
...  
Keyword(s):  
Squeeze Casting ◽  
Die Casting ◽  
Dendritic Structure ◽  
Casting Process ◽  
Die Design ◽  
Main Bearing ◽  
Block Based ◽  
Semi Solid ◽  
Bearing Cap ◽  
Squeeze Casting Process

There are two new processes to development automobile structural components which have certain thickness. In the present paper, taking a main bearing cap product as an example, analyses die design by comparing the experimental and computational numerical simulation results. For the main bearing cap, product structure and mold design were designed to be suitable for characters of SSM die casting and squeeze process. Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity and solid fraction phase make the flow condition more laminar than liquid squeeze casting with the partial fill experiment. And compared with squeeze casting process, the globular shape grain size is smaller than dendritic structure. And mechanical property result shows that the elongation of SSM die casting can achieve more than twice than squeeze casting.

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