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Rare Metals 2006年第2期25卷 177-183页

作者： LIU Zheng MAO Weiming ZHAO Zhengduo Material of Science and Engineering School University of Science and Technology Beijing Beijing 100083 China Faculty of Material and Chemical Engineering Jiangxi University of Science and Technology Ganzhou 341000 China

The semi-solid slurry of a hypoeutectic Al-Si alloy was manufactured by low superheat pouring and weak electromagnetic stirring. The effects of pouting temperature and stirring power on the semi-solid slurry were investigated. The results indicated that the semi-solid slurry to satisfy rheocasting can be manufactured by low superheat pouring and weak electromagnetic stirring. The pouring temperature （or superheat） and the stirring power remarkably affected the morphology of primary α-Al and the size of primary α-Al, and there is no obvious effect of stirring time on primary α-Al. Compared with the samples made by low superheat pouring with no stirring, the nucleation rate, particle morphology and grain size of primary α-Al in A356 were markedly improved by low superheat pouring and weak electromagnetic stirring. On the condition of weak electromagnetic stirring, the pouring temperature with low superheat can be suitably raised to reach the effectiveness obtained from the lower pouring temperature without stirring.

关键词： semi-solid low superheat pouring weak electromagnetic stirring hypoeutectic Al-Si alloy A356 Al alloy

EFFECT OF GRAIN REFINING ON PRIMARYαPHASE IN SEMI-SOLID A356 ALLOY PREPARED BY low superheat pouring AND SLIGHT ELECTROMAGNETIC STIRRING

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 57-64页

作者： Z. Liu W.M. Mao Z.D. Zhao Faculty of Material and Chemical Engineering Jiangxi University of Science and Technology Ganzhou 341000 China School of Material Science and Engineering University of Science ＆ Technology Beijing Beijing 100083 China

The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.

关键词： Semi-solid Grain-refined low superheat pouring Slight electromagnetic stirring A356 alloy Al-Ti-B

Microstructural characteristics of in situ Mg_2Si/Al-Si composite by low superheat pouring

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China Foundry 2013年第5期10卷 282-287页

作者： Wu Xiaofeng Wang Zhe Zhang Guangan Wu Fufa School of Materials Science Engineering Liaoning University of Technology

To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three AI-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring （LSP） process. The effects of the pouring temperature （superheat） on the morphology and size distribution of primary phases （primary e-AI and Mg2Si）, binary （a-AI ＋ Mg2Si） eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature （superheat） not only refines the grain structure of the primary e-AI and binary （e-AI ＋ Mg2Si） eutectic cell in three composites and promotes the formation of more non- dendritic structural semi-solid metal （SSM） slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

关键词： Mg2 Si/Al-Si composite semi-solid metal slurry low superheat pouring microstructure

Rheo-squeeze casting of semi-solid A356 aluminum alloy slurry

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1769-1773页

作者：毛卫民郑秋朱达平 School of Materials Science and Engineering University of Science and Technology Beijing

The effect of pouring temperature, electromagnetic stirring power and holding process on semi-solid A356 aluminum alloy slurry was investigated, then the slurry was squeeze-cast. The results show that when the pouring temperatures are properly above the liquidus line, for example 630-650 ℃, the slurry with spherical primary α（Al） grains can be prepared under the stirring power of 1.27 kW. The slurry is then homogeneously held for a short time, and the primary α（Al） grains are further ripened and distributed evenly in the slurry. The results of the rheo-squeezed casting experiments show that the injection specific pressure has a great effect on the filling ability of the semi-solid A356 aluminum alloy slurry, and the higher the injection specific pressure is, the better the ability for the slurry to fill the mould cavity is. When the injection specific pressure is equal to or above 34 MPa, the whole and compact rheo-squeezed castings can be obtained. The microstructure of the castings indicates that the shape, size and numbers of the primary α（Al） grains in different parts of the castings are highly consistent. After being held at 535 ℃ for 5 h and then aged at 155 ℃ for 12 h, the ultimate strength of the rheo-squeezed castings can reach 300-320 MPa, the yield strength 230-255 MPa, and the elongation 11%-15%.

关键词： low superheat pouring weak electromagnetic stirring semi-solid A356 alloy rheo-squeeze casting