Structure and properties of 6061 + 26 mass % Si aluminum alloy produced via coupled rapid solidification and KOBO-extrusion of powder

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• 作者：Ludwik Blaz ; Makoto Sugamata ; Junichi Kaneko ; Jakub Sobota ; Grzegorz Wloch ; Wlodzimierz Bochniak ; Anna Kula
• 关键词：Aluminum silicon alloy ; Hot deformation ; Rapid solidification ; Powder metallurgy ; Extrusion ; Microstructure
• 刊名：Journal of Materials Processing Technology
• 出版年：2009
• 出版时间：1 May 2009
• 年：2009
• 卷：209
• 期：9
• 页码：4329-4336
• 全文大小：1200 K

文摘

Experiments on mechanical consolidation of rapidly solidified (RS) powder of 6061 + 26 mass % Si alloy were performed using the oscillating-die extrusion method. The RS powder was wrapped in thin-wall 6061-alloy cup 35 mm in diameter and vacuum-compressed by means of 100 ton press. Bars 8 mm in diameter were extruded with cross-section reduction of λ = 19 without any preheating of the charge. Tubes with a diameter/wall thickness of 14 mm/1 mm and cross-section reduction of λ = 33 were also manufactured with success. TEM/STEM observations revealed a very fine structure of as-extruded material and bimodal distribution of quasi-spherical silicon particles. Statistical analysis revealed a silicon fine fraction of 0.1–0.7 μm and a coarse fraction 2.1–2.5 μm in diameter. Examination by means of TEM did not reveal any significant changes in the morphology of the silicon particles, even when a high extrusion ratio and the material annealing after deformation were used. Hot compression tests on as-extruded rods (λ = 19) and preliminary annealed samples were performed at a constant true strain rate of 5 × 10⁻³ s⁻¹ within the temperature range of 293–823 K. High strength of the material and relatively high ductility of samples deformed by compression up to _t  0.4 were observed. The maximum flow stress value for as-extruded material was reduced with deformation temperature from 390 to 3.5 MPa for 293 and 823 K, respectively. Annealing of the samples at 773 K/30 min was found to reduce the maximum flow stress by 30–40 % . Tensile strengths of similar as-cast alloys and materials manufactured by means of other powder metallurgy methods were shown for the purpose of comparison.