Papers by Keyword: Hypereutectic Al-Si

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Authors: K. Pratheesh, M. Ravi, Allesu Kanjirathikal, M.A. Joseph, P. Karrupuswamy
Abstract: The explorative attempt to harness new materials that could be utilized for manufacturing products with sophisticated geometry for aerospace and automotive applications necessitate the exploitation of Al-Si-Mg alloy family. Al-14Si alloys which posses 1% Mg exhibits a microstructure that contains primary Si particles, eutectic Si and Mg2Si in α-Al matrix. With a view to improve the mechanical properties of this alloy, Sr modification was carried out by adding 0.04% Sr to the molten metal. The Mg2Si phase has high melting temperature, low density, high hardness, low co-efficient of thermal expansion and high elastic modulus. The best results in the microstructure were obtained through a combination of Sr addition and T6 heat treatment which enhances the mechanical properties and wear resistance of the alloy Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}
Authors: Yong Jin Kim, L.F. Wang, In Sang Chung, Jin Chun Kim, Tae Suk Jang
Abstract: The hypereutectic prealloyed Al-Si powders were prepared by gas atomization process. The microstructure and compacting ability of the atomized Al-Si powders were investigated. With increasing the gas pressure of the atomization, the average powder size and oxygen content were decreased. The size of primary eutectic Si particles in the as-atomized powders was about 8~10. As-atomized powders were hot-pressed into a cylindrical shape. Relative density of the hot-pressed samples was achieved about 96~99 % of theoretical density. Some properties of the samples were evaluated in this paper.
Authors: Jaroslaw Piątkowski
Abstract: The paper presents the results of microscopic examinations of the growth of primary silicon crystals in hypereutectic A390.0 (AlSi17Cu5Mg) silumin. A diagram of the growth of primary silicon crystals in the melt without overheating and superheated to a temperature of 920°C has been presented. From the experimental results obtained on crystal morphologies of primary silicon, different sequences of crystal growth of the primary silicon can be expected. In the silumin without overheating, five-pointed star-shaped particles form, after superheating, the crystals of primary silicon take more compact shapes. This structure provides better mechanical properties and thus increases the area of application of alloys with hypereutectic silicon content.
Authors: H.S. Kang, W.Y. Yoon, Kwon H. Kim, M.H. Kim, Eui Pak Yoon
Abstract: Microstructural variation is quantitatively characterized by measured undercooling. For neareutectic Al-13wt%Si alloys, microstructure transitions, which include a phase change from eutectic to primary α-Al dendrite plus eutectic and a morphological change from α-Al dendrite to equiaxed Al grains, were observed with increasing undercooling levels. For hypereutectic Al-Si alloys, microstructure transitions, which include a morphological change of primary and eutectic Si crystals, were also obtained quantitatively by increasing undercooling.
Authors: Mentin Yilmaz, S. Altıntaş
Authors: Jung Pyung Choi, Won Jung Kim, Tae Woon Nam, Eui Pak Yoon
Abstract: This paper investigates the effect of Bubbling and AlCuP on primary Si size in Al-18%Si alloy. Bubbling process and AlCuP treatment are effective for refining primary Si in hypereutectic Al-Si alloy. Both the bubble and AlCuP can be used as nucleation sites of primary Si. Many nucleation sites can make the size of primary Si decreased. So, this experiment suggests that the mix using of bubbling process and AlCuP treatment are more effective for nucleation site of primary Si. For deciding the optimum treatment order, the experiments are processed 3 kinds of order with varying stirring time and holding temperature; 1)AlCuP treatment and then bubbling process, 2)simultaneously using of bubbling process and AlCuP treatment, 3)bubbling process and then AlCuP treatment.
Authors: M. Faraji, Iain Todd, H. Jones
Abstract: The effect of size refinement of primary silicon and modification of eutectic silicon, separately and simultaneously, on microstructure of hypereutectic Al-20wt%Si has been investigated under different casting conditions. Results showed that number per unit volume of primary silicon particles was doubled by inoculation with 0.02% phosphorus in the alloy with 0.0015% phosphorus already in it, whereas 70% of a small ingot (40×35 mm) became modified eutectic, and the formation of primary silicon was suppressed, on adding 0.1% strontium. Simultaneous addition of phosphorus and strontium still refined the primary silicon but did not modify the eutectic. Addition of strontium alone caused roughening of the primary silicon, exemplified by increased undercooling registered on the cooling curve. Also crystallographic relationships between polyhedral primary silicon particles have been investigated by Electron Back Scattered Diffraction (EBSD).
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