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Grain refinement of primary silicon in hypereutectic Al-Si alloys by different P-containing compounds

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China Foundry 2021年第1期18卷 37-44页

作者： Benson Kihono Njuguna Jia-yan Li Yi Tan Qian-qian Sun Peng-ting Li School of Materials Science and Engineering Dalian University of TechnologyDalian116024China State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai200444China Shandong Shanda Al&Mg Melt Technology Company Limited Jinan250061China

The grain refinement behavior of Si-3 P,Si-25 Mn-10 P,and Al-10 Si-2 Fe-3 P master alloys on hypereutectic Al-24 Si alloy was *** analysis indicates that the P-containing compounds in the three master alloys are Si P,Mn P,and Al P,*** coarse flower-like primary silicon in the Al-24 Si alloy transforms into smaller,well-distributed blocks with the addition of various master *** pouring at 840°C,the average grain size of the primary silicon refined by Si-25 Mn-10 P master alloy with a holding time of 30 min is about 18μm,which is significantly smaller than those refined by Si-3 P and Al-10 Si-2 Fe-3 P master *** grain size shows an increasing trend when the holding time is further *** holding temperature has a positive effect on the grain refinement of Si-25 Mn-10 P master *** grain refinement mechanism of the three master alloys was also discussed.

关键词： grain refinement primary silicon master alloy AlP compound

Effects of melt viscosity on enrichment and separation of primary silicon from Al-Si melt

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Transactions of Nonferrous Metals Society of China 2017年第2期27卷 467-474页

作者：余文轴马文会郑忠蒋伟燕李杰田茂洪重庆大学材料科学与工程学院重庆400044 昆明理工大学冶金与能源工程学院昆明650093

The effects of melt viscosity on the enrichment and separation of Si crystals from Al–Si melt during an electromagnetic solidification process were investigated. Both the enrichment efficiency and the separation were found to be strongly dependent on the melt viscosity. A high melt viscosity was beneficial to the enrichment of primary silicon, whereas a low melt viscosity facilitated the separation process. A new enrichment mechanism was proposed in order to clarify the influence of melt viscosity, and an improved process for achieving high-efficiency enrichment of Si crystals via control of the melt viscosity was also proposed. Additionally, the morphology of Si crystals was found to change from spheroidal to plate-like in shape owing to the difference in viscosities in different regions.

关键词： directional solidification electromagnetic stirring Al-Si melt primary silicon separation viscosity

Growth mechanism of primary silicon in cast hypoeutectic Al-Si alloys

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Transactions of Nonferrous Metals Society of China 2012年第6期22卷 1264-1269页

作者：王守仁马茹王英姿王勇杨丽颖济南大学机械工程学院济南250022 济南大学材料科学与工程学院济南250022 济南大学物理科学学院济南250022

The microstructural features of hypoeutectic AI-10%Si alloy were observed using optical microscopy and electron backscatter diffraction. The results show that primary silicon particles are frequently found in hypoeutectic alloys. Hence, the nucleation and growth mechanisms of the precipitation of primary silicon of hypoeutectic Al-10%Si alloy melts were investigated. It was discovered that Si atoms are easy to segregate and form Si-Si clusters, which results in the formation of primary silicon even in eutectic or hypoeutectic Al-Si alloys. In addition, solute redistribution caused by chemical driving force and large pile-ups or micro-segregation of the solute play an important role in the formation of the primary silicon, and the solute redistribution equations were derived from Jackson-Chalmers equations. Once Si solute concentration exceeds eutectic composition, primary silicon precipitates are formed at the front of solid/liquid interface.

关键词： Al-Si alloys solidification crystal growth primary silicon solute redistribution

Effects of individual and combined additions of phosphorus,boron and cerium on primary and eutectic silicon in an Al-30Si alloy

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Rare Metals 2009年第6期28卷 651-655页

作者： DAI Hongshang LIU Xiangfa Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials（Ministry of Education of China） Shandong University Jinan 250061 China Shandong Binzhou Bohai Piston Co. Ltd. Binzhou 256602 China

The modification of silicon in an Al-30Si alloy was studied using optical microscopy, electron probe micro-analysis, transmission electron microscopy and differential scanning calorimetry. It is found that phosphorus master alloys combined with boron master alloys have good modification effect on primary silicon but no evident modification effect on eutectic silicon, while boron combined with cerium has good modification effect on eutectic silicon. The results of differential scanning calorimetry show that phosphorus, boron or cerium addition and their combined addition have different undercooling effects on eutectic silicon. Many scholars thought that AlP particles were the nuclei of eutectic silicon when phosphorus was enough in the alloy. Our results show that β-（Al,Si,Fe） can still be the nucleus of plate-like entectic silicon while AlP is the nucleus of primary silicon when there is enough phosphorus in the melt. In addition, the mechanism about the modification was also discussed.

关键词： Al-Si alloy eutectic silicon primary silicon modification refinement

Refinement and migrating behaviors in Al-Si hypereutectic alloys solidified under electromagnetic vibration

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Acta Metallurgica Sinica(English Letters) 2011年第4期24卷 301-308页

作者： Jianbo YU Zhongming REN Kan9 DENG Shanghai Enhanced Laboratory of Ferro-Metallurgy Shanghai University Shanghai 200072 China

The effects of electromagnetic vibration （EMV） on the refinement and migration of primary silicons in the A1-18 wt pct Si alloy were investigated systematically. It was found that EMV could effectively refine primary silicons. The equivalent diameter of primary silicon first decreases slowly with the current increasing from 1 A to 3 A, but then drops rapidly between 3 A and 10 A, next gradually decreases with increasing current intensity. When the EMV intensity was low, the primary silicons were agglomerated and expelled to the top of a sample, the segregation of silicon grains gradually decreased and the agglomerating phenomena disappeared with the increase of EMV intensity, and the star-like coarse primary silicons turned refined flake or square morphology. The refinement and migration of primary silicons depended on the Lorentz force, gravity and the effective viscous force.

关键词： High magnetic field Electromagnetic vibration HypereutecticAl-Si alloys primary silicon Refinement Migrating

Effect of solidification cooling rate on microstructure and tribology characteristics of Zn-4Si alloy

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International Journal of Minerals,Metallurgy and Materials 2024年第2期31卷 362-373页

作者： F.Akbari M.Golkaram S.Beyrami G.Shirazi K.Mantashloo R.Taghiabadi M.Saghafi Yazdi I.Ansarian Department of Metallurgy and Material Science Imam Khomeini International University(IKIU)Qazvin ***Iran

The main objective of this work was to modify the microstructure and enhance the tribological properties of a new Zn-4Si al-loy through a high solidification cooling rate(SCR).According to the results,by increasing the SCR from 2.0 to 59.5℃/s the average size of primary Si particles and that of the grains reduced from 76.1 and 3780μm to less than about 14.6 and 460μm,***-ing the SCR also enhanced the microstructural homogeneity,decreased the porosity content(by 50%),and increased the matrix hardness(by 36%).These microstructural changes enhanced the tribological *** instance,under the applied pressure of 0.5 MPa,an in-crease in the SCR from 2.0 to 59.5℃/s decreased the wear rate and the average friction coefficient of the alloy by 57%and 23%,*** wear mechanism was also changed from the severe delamination,adhesion,and abrasion in the slowly-cooled alloy to the mild tribolayer delamination/abrasion in the high-cooling-rate-solidified sample.

关键词： zinc-silicon alloy primary silicon solidification cooling rate tribology sliding wear

Effects of P+Cr complex modification and solidification conditions on microstmcture of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

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China Foundry 2014年第6期11卷 481-486页

作者： Zhang Haitao Zuo Kesheng Han Xing Shao Bo Qin Ke Cui Jianzhong Key Lab of Electromagnetic Processing of Materials Ministry of Education Northeastern University

Large and segregated primary Si particles may drastically decrease the mechanical properties of AI-Si alloys. To solve this problem, a P-Cr complex modifier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic AI-Si alloys. The segregation of primary Si can be inhibited by adding a P＋Cr complex modifier and increasing the cooling rate during solidification. The refinement of primary Si particles by P＋Cr complex modification is due to the formation of CrSi2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrSi2 particles to the primary Si particles.

关键词： hypereutectic Al-Si alloys primary silicon P-Cr complex modifier cooling rate

Effect of Nd on Microstructure and Mechanical Properties of Hypereutectic Al-25Si Alloy

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Journal of Rare Earths 2007年第S1期25卷 473-476页

作者：高波陈磊孙树臣涂赣峰田小梅赵铁钧吴文远边雪 School of Materials and Metallurgy Northeastern University

The modification mechanism of Nd on Al-25Si alloy was studied. The result showed that pure Nd (0.3%) could significantly refine primary silicon in hypereutectic Al-25Si alloy. And the morphology of primary silicon was transformed from star-shaped to block and the size of primary silicon changed from 150～200 μm to 40～80 μm after modification. The morphology of silicon and elements presence was detected by means of SEM-EDS, XRD was carried out to detect the phase constitution before and after modification. It was found that no new phase formed and the lattice of silicon and aluminum increased after modification and most of Nd may exist as solids solute element of silicon and absorb on the surface of silicon. Mechanical property test results showed that after modification with 0.3% Nd, Tensile strength increased about 33% from 138 to 184 MPa, yield strength increased about 15% from 126 to 145 MPa, and elongation change was not obvious. The improvement of mechanical property should attribute to fine grain strength and purification of base metal after modification.

关键词： primary silicon Neodymium modification hypereutectic Al-Si alloy rare earths

Si purification by enrichment of primary Si in Al-Si melt

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Transactions of Nonferrous Metals Society of China 2013年第11期23卷 3476-3481页

作者：余文轴马文会吕国强任永生薛海洋戴永年昆明理工大学冶金与能源工程学院昆明650093 昆明理工大学真空冶金国家工程实验室昆明650093

The primary silicon crystals and AI-Si alloy in hypereutectic A1-Si melt were separated by electromagnetic stirring and directional solidification. Additionally, the distribution feature of impurities in A1-Si system was verified. The results show that the impurities are mainly located in A1-Si alloy and the grain boundaries between the A1-Si alloy and primary silicon. Furthermore, the morphology of primary silicon changes from fish-bone like to plate like and spheroid due to the different Si contents. The amount of impurities decreases with the increasing of Si content in different positions of the sample. The amount of impurities in the bottom of the sample is approximately 10× 10^-6, which is obviously improved compared with the 1248.47 × 10^- 6 in metallurgical Si.

关键词： primary silicon A1-Si alloy electromagnetic stirring directional solidification impurity