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Research and Applications of semi-solid processing

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Rare Metals 2001年第2期20卷 74-77页

作者： Kui Zhang, Jun Xu, Likai Shi, Daijin Cui, Yuxin Zheng (General Research Institute for Nonferrous Metals, Beijing 100088, China Dongfeng Motor Corp., Shiyan 442001, China) 北京有色冶金研究总院北京 100088 东风汽车公司湖北十堰 100088 东风汽车公司湖北 100088

It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial applications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as 'elephant foot' and 'periphery liquid metal loss' during reheating could be avoided through controlling the non-dendritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-solid die-casting are fairly different from those of liquid die-casting.

关键词： semi-solid processing Al-Si alloy automotive component die casting

Application of cyclic upsetting-extrusion to semi-solid processing of AZ91D magnesium alloy

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Transactions of Nonferrous Metals Society of China 2013年第4期23卷 909-915页

作者：陶健全姜巨福陈红肖远伦张荣朝胡庆华赵军赵强西南技术工程研究所重庆400039 哈尔滨工业大学材料科学与工程学院哈尔滨150001

The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.

关键词： AZ91D magnesium alloy semi-solid processing cyclic upsetting-extrusion mechanical properties microstructure

Melting behavior and globular microstructure formation in semi-solid CoCrCuxFeNi high-entropy alloys

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Journal of Materials Science & Technology 2020年第17期52卷 207-217页

作者： Kaio Niitsu Campo Caio Chaussêde Freitas Leonardo Fanton Rubens Caram University of Campinas School of Mechanical EngineeringSPBrazil

High-entropy alloys can be compelling raw materials for semi-solid *** the present study,the influence of the Cu content on the melting behavior and semi-solid microstructure of CoCrCuxFeNi(x=0,1,2,3)alloys was ***-melted samples were cross-rolled at room temperature and then isothermally treated at 1175℃in the semi-solid state for 300 *** characterization showed that the alloys containing Cu were formed by two fcc ***,the increase in Cu content also led to an increase in the volumetric fraction of the Cu-rich *** solidification,this phase,which is the last to form,nucleates and epitaxially grows on the Cu-lean *** the studied CoCrCuFeNi alloys exhibited the same melting *** Cu-rich phase melts at approximately 1120℃,whereas the Culean phase melts at approximately 1350℃,providing a suitable processing temperature range of more than 200℃.The semi-solid microstructures were considerably refined and globular regardless of the alloy composition,being suitable for semi-solid ***,each fcc phase exhibited roughly the same composition under the different processing *** Cu content in the Cu-lean phase was approximately 10 at.%,while Co,Cr,Fe,and Ni were in an approximately equiatomic ***,the Cu content was between 80 at.%and 86 at.%in the Cu-rich *** isothermal treatment of the CoCrCu3FeNi alloy at a higher temperature(1300℃)only caused the globules to *** conclusion,this work showed that these alloys can be potential candidates for semi-solid processing.

关键词： semi-solid processing Thixoforming High-entropy alloys Microstructure

Structural evolution of spray-formed Al-70wt.%Si alloys during iso-thermal holding in the semi-solid state

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Rare Metals 2005年第4期24卷 317-324页

作者： ZHANG Di CUI Hua WEI Yanguang ZHANG Jishan ZHANG Yongan XIONG Baiqing The State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China General Research Institute for Nonferrous Metals Beijing 100088 China

The grain growth behavior of spray-formed Al-70wt.%Si alloys was studied in the semi-solid state. The specimens were isothermally heat-treated at various temperatures between the solidus and liquidus of Al-Si alloys and then quenched in water. The microstructure of reheated specimens was characterized using optical and scanning electron microscopies. The isothermal holding experiment was carried out to investigate grain growth behavior as a function of holding time and temperature in the semi-solid state. The coarsening mechanism and the effect of porosity on microstructure were also studied.

关键词： materials science grain growth behavior spray forming Al-70wt.%Si alloys semi-solid processing

Deformation mechanism and forming properties of 6061Al alloys during compression in semi-solid state

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1725-1730页

作者：尚淑珍路贵民唐小玲赵祖欣吴成明 Key Laboratory of Safety Science of Pressurized System Ministry of EducationEast China University of Science and Technology Zhejiang Geely Automobile Research Institute Co. Ltd.

The 6061 semi-solid aluminium alloy feedstocks prepared by near-liquidus casting were compressed in semi-solid state by means of Gleeble-3500 thermal-mechanical *** relationship between the true stress and the true strain at different temperatures and strain rates was studied with the deformation degree of 70%.The microstructures during the deformation process were *** deformation mechanism and thixo-forming properties of the semi-solid alloys were *** results show that the homogeneous and non-dendrite microstructures of semi-solid 6061Al alloy manufactured by near-liquidus casting technology could be transformed into semi-solid state with the microstructure suitable for thixo-forming which are composed of near-spherical grains and liquid phase with eutectic composition through reheating *** deformation temperature and strain rate affect the peak stress significantly rather than steady flow *** resistance to deformation in semi-solid state decreases with the increase of the deformation temperature and decrease of the strain *** steady thixotropic deformation stage, the thixotropic property is uniform, and the main deformation mechanism is the rotating or sliding between the solid particles and the plastic deformation of the solid particles.

关键词： semi-solid processing 6061Al alloy compression deformation microstructural evolution thixotropic property

RHEOCASTING OF A356 ALLOY BY LOW SUPERHEAT POURING WITH A SHEARING FIELD

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 328-334页

作者： H.M. Guo X.J. Yang B. Hu Department of Materials Science and Engineering Nanchang UniversityNanchang 330031 China Department of Mechanical and Electronic Engineering Nanchang UniversityNanchang 330031 China

A novel semi-solid slurry-making process was developed, which was a controlled nucleation and growth technique using a specially designed rotational barrel. Experimental study was undertaken to investigate the effects of pouring temperature and rotation speed of barrel on the microstructure of A356 alloy. Localized rapid cooling, combined with vigorous mixing during the initial stage of solidification enhanced wall nucleation and nuclei survival. High nuclei density combined with a much gradual cooling afterwards led to the formation of the near-ideal semi-solid slurry under a large processing window for the pouring temperature. Primal. phase presented in mean equivalent diameter of 50-701μm and shape factor of 0.812-0.847, and featured zero-entrapped eutectic.

关键词： semi-solid processing nucleation grainsgrowth interfacestability

Effects of Cr and Cr/Mn Combined Additions on semi-solid Microstructures of Al-Mg-Si Alloys Produced by D-SSF Process

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Journal of Materials Science & Technology 2008年第1期24卷 21-24页

作者： Witthaya Eidhed Hiroyasu Tezuka Tatsuo Sato Faculty of Engineering King Mongkut's Institute of Technology North Bangkok Thailand Department of Metallurgy and Ceramic Sciences Tokyo Institute of Technology Japan

The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are *** the Cr-added alloy,the Al-7Cr compound is formed with homogeneously distributed in theα-Al matrix after *** of the Al-7Cr andα-Al-（12）Mn3-Si-2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added *** the semi-solid microstructures,the smallestα-Al grains are obtained in the 60% cold-rolled *** prolonged holding time,theα-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added *** deformation by cold-rolling accelerates spheroidization of theα-Al *** D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.

关键词： D-SSF process semi-solid processing Thixoforming AI-Mg-Si alloy

Microstructural Evolution during Partial Remelting of Al—Si Alloys Containing Different Amounts of Magnesium

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Journal of Materials Science & Technology 2013年第10期29卷 971-978页

作者： A.Abedi M.Shahmiri B.Amir Esgandari B.Nami Department of Mechanical Engineering Shahid Rajaee Teacher Training University (SRTTU) School of Metallurgy and Materials Science Iran University of Science and Technology (IUST)

The effect of magnesium on the microstructures of A356 aluminum alloy in as-cast and semi-solid conditions was investigated. The result showed that magnesium refined the size of primary α（Al） phase and eutectic silicon. Magnesium also modified considerably the eutectic silicon and decreased the size of globular α（Al） solid phase in the semi-solid processed alloy. Coarsening rate of the solid α（Al） phase during partial remelting at semi-solid temperature decreased by adding magnesium, probably due to the decrease of both the solid- liquid interfacial energy and inter-diffusion coefficient of solute atoms.

关键词： Al--Si alloys Magnesium Microstructure semi-solid processing Coarsening

Theory and application research development of semi-solid forming in China

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1805-1814页

作者：罗守靖姜永正康永林 School of Materials Science and Engineering Harbin Institute of Technology Ka Shui International Holdings Ltd School of Materials Science and Engineering University of Science and Technology Beijing

In order to adapt to the trend of ＂energy saving and emission reduction＂ and impel the practical application of semi solid processing （SSP） in China, the progress and application of semi-solid theory in China have been reviewed briefly and systematically. It was emphasized on basic theories, such as formation of globular grains, theology, high pressure solidification and plastic deformation and applications, such as material design, preparation of semi-solid billets （slurries）, thixoforming and application status, which are based on the advantage of semi-solid processing. The results show that the gap of SSP between world level and China exists, especially in application technologies, including market recognition, application fields exploiting, developing of billets （slurries） preparation technologies with low cost and special equipments. The prospect of semi-solid forming development path in China is presented. And we hope that application of SSP has great new breakthrough and development and China wilt be changed from a large metal processing country to a powerful metal processing country.

关键词： semi-solid processing theory production forming