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Microstructure and properties of high silicon aluminum alloy with 2% Fe prepared by rheo-casting

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1603-1607页

作者：钟鼓吴树森安萍毛有武李世钊 State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology

The morphology changes of both Fe-containing intermetallic compounds and the primary Si phase of Al-20Si-2Fe- 2Cu-0.4Mg-1.0Ni-0.5Mn （mass fraction, %） alloy produced by semi-solid rheo-diecasting were studied. The semi-solid slurry of high silicon aluminum alloy was prepared by direct ultrasonic vibration （DUV） which was imposed on the alloy near the liquidus temperature for about 2 rain. Then, standard test samples of 6.4 mm in diameter were formed by semi-solid rheo-diecasting. The results show that the DUV treatment suppresses the formation of needle-like ,β-Al5（Fe,Mn）Si phase, and the Fe-containing intermetallic compounds exist in the form of fine Al4（Fe, Mn）Si2 particles. Additionally, the primary Si grows up as fine and round particles with uniform distribution in α（Al） matrix of this alloy under DUV treatment. The tensile strengths of the samples at the room temperature and 573 K are 230 MPa and 145 MPa, respectively. The coefficient of thermal expansion （CTE） between 25 ℃ and 300 ℃ is 16.052 8×10^-6 ℃^-1, and the wear rate is 1.55%. The hardness of this alloy with 2% Fe reaches HB146.3. It is discovered that modified morphology and uniform distribution of the Fe-containing intermetallic compounds and the primary Si phase are the main reasons for reducing the CTE and increasing the wear resistance of this alloy.

关键词： high silicon aluminum alloy ultrasonic vibration rheo-casting rnicrostructure mechanical properties

Dry wear behavior of rheo-casting Al-16Si-4Cu-0.5Mg alloy

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Transactions of Nonferrous Metals Society of China 2016年第11期26卷 2818-2829页

作者：胡钊华吴国华徐佳莫文飞李艳磊刘文才张亮丁文江 Jonathan QUAN Yuan-Wei CHANG 上海交通大学轻合金精密成型国家工程研究中心与金属基复合材料国家重点实验室上海200240 Department of Materials Science and Engineering University of California Los Angeles

Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of the alloy were carried out byoptical microscope and scanning electron microscope. The microstructural analysis showed that via rheo-processing, the primary Siwas refined and rounded, eutectics dispersed more homogenously, and even the skeleton AlFeMnSi phase was fragmented into facetshape. Micro-scratch test showed that the microstructural refinement resulted in better wear resistance. Dry sliding wear test revealedthat the rheo-processed sample exhibit obviously superior wear resistance because of the microstructure improvement. The dominantmechanism in mild wear condition is abrasion, but it turned to adhesion and oxidation in high applied load and fast sliding velocityconditions.

关键词： rheo-casting aluminum alloy dry wear micro-scratch

Microstructure evolution and mechanical properties of rheo-processed ADC12 alloy

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Transactions of Nonferrous Metals Society of China 2016年第12期26卷 3070-3080页

作者： Zhao-hua HU Xiang PENG Guo-hua WU Da-qiang CHENG Wen-cai LIU Liang ZHANG Wen-jiang DING National Engineering Research Center of Light Alloys Net Forming and State Key Laboratory of Metal Matrix Composite Shanghai Jiao Tong University 200240 Shanghai China

Microstructure evolution and mechanical properties of the rheo-processed ADC12 alloy were investigated by means ofoptical microscopy, X-ray diffraction and scanning electron microscopy. Primary dendritic Al of rheo-casting (RC) andrheo-diecasting (RDC) ADC12 alloys are sheared off. The average size, as well as solid fraction of the primary Al increase withdescending pouring temperature. The mechanical properties of alloys are strengthened by rheo-processing. Ultimate tensile strengthsof RC samples increase with the decrease of the pouring temperature, and reach the maximum in the range from 580 to 600 °C. Atpouring temperature of 595 °C, the RDC sample obtains the best ultimate tensile strength and elongation. Great reductions onporosity and primary Al globularization are crucial to the mechanical properties. Relationships of the primary Al size and yield stressare depicted with Hall?Petch equation.

关键词： aluminum alloy casting rheo-processing rheo-casting rheo-diecasting mechanical properties