“…2 and 3 may also be observed in 2D. This microstructure exhibits a classical globular/dendritic grain morphology with inter-dendritic second phases characteristic of A356 alloys 58 – 61 . Figure 5 Representative optical micrographs of polished sections for a representative cell showing ( a ) a corner, ( b ) a vertical strut and ( c ) a horizontal rib.…”
Section: Resultsmentioning
confidence: 85%
“…2 and 3 may also be observed in 2D. This microstructure exhibits a classical globular/dendritic grain morphology with inter-dendritic second phases characteristic of A356 alloys [58][59][60][61] . www.nature.com/scientificreports/ Figure 6 illustrates the size and shape/morphology of the α-Al grains characteristic of different locations.…”
Section: Microstructural Characterization Of the Cast Lattice Structumentioning
confidence: 87%
“…A356 is the most common Al alloy used to cast components for transportation industries due to its capability to be cast in ceramic block to produce thin-walled and complex geometries 58 . As a hypoeutectic aluminium alloy, the microstructural characterization of A356 is often concerned with the size and shape of the α-Al matrix [58][59][60][61] , eutectic Si [62][63][64][65] , Mg 2 Si and Fe-based intermetallic compounds [66][67][68][69] , such as Chinese script-shaped α-Al8Fe2Si and needle-shaped β-Al 5 Fe 2 Si. In as-cast samples, previous to solution treatment, Mg 2 Si are precipitated in the grain boundaries 70,71 and, due to the presence of Mg, Chinese script-shaped π-Al 8 FeMg 3 Si 6 may also be observed 48,49 .…”
Cellular materials are recognized for their high specific mechanical properties, making them desirable in ultra-lightweight applications. Periodic lattices have tunable properties and may be manufactured by metallic additive manufacturing (AM) techniques. However, AM can lead to issues with un-melted powder, macro/micro porosity, dimensional control and heterogeneous microstructures. This study overcomes these problems through a novel technique, combining additive manufacturing and investment casting to produce detailed investment cast lattice structures. Fused filament fabrication is used to fabricate a pattern used as the mold for the investment casting of aluminium A356 alloy into high-conformity thin-ribbed (~ 0.6 mm thickness) scaffolds. X-ray micro-computed tomography (CT) is used to characterize macro- and meso-scale defects. Optical and scanning electron (SEM) microscopies are used to characterize the microstructure of the cast structures. Slight dimensional (macroscale) variations originate from the 3D printing of the pattern. At the mesoscale, the casting process introduces very fine (~ 3 µm) porosity, along with small numbers of (~ 25 µm) gas entrapment defects in the horizontal struts. At a microstructural level, both the (~ 70 μm) globular/dendritic grains and secondary phases show no significant variations across the lattices. This method is a promising alternative means for producing highly detailed non-stochastic metallic cellular lattices and offers scope for further improvement through refinement of filament fabrication.
“…2 and 3 may also be observed in 2D. This microstructure exhibits a classical globular/dendritic grain morphology with inter-dendritic second phases characteristic of A356 alloys 58 – 61 . Figure 5 Representative optical micrographs of polished sections for a representative cell showing ( a ) a corner, ( b ) a vertical strut and ( c ) a horizontal rib.…”
Section: Resultsmentioning
confidence: 85%
“…2 and 3 may also be observed in 2D. This microstructure exhibits a classical globular/dendritic grain morphology with inter-dendritic second phases characteristic of A356 alloys [58][59][60][61] . www.nature.com/scientificreports/ Figure 6 illustrates the size and shape/morphology of the α-Al grains characteristic of different locations.…”
Section: Microstructural Characterization Of the Cast Lattice Structumentioning
confidence: 87%
“…A356 is the most common Al alloy used to cast components for transportation industries due to its capability to be cast in ceramic block to produce thin-walled and complex geometries 58 . As a hypoeutectic aluminium alloy, the microstructural characterization of A356 is often concerned with the size and shape of the α-Al matrix [58][59][60][61] , eutectic Si [62][63][64][65] , Mg 2 Si and Fe-based intermetallic compounds [66][67][68][69] , such as Chinese script-shaped α-Al8Fe2Si and needle-shaped β-Al 5 Fe 2 Si. In as-cast samples, previous to solution treatment, Mg 2 Si are precipitated in the grain boundaries 70,71 and, due to the presence of Mg, Chinese script-shaped π-Al 8 FeMg 3 Si 6 may also be observed 48,49 .…”
Cellular materials are recognized for their high specific mechanical properties, making them desirable in ultra-lightweight applications. Periodic lattices have tunable properties and may be manufactured by metallic additive manufacturing (AM) techniques. However, AM can lead to issues with un-melted powder, macro/micro porosity, dimensional control and heterogeneous microstructures. This study overcomes these problems through a novel technique, combining additive manufacturing and investment casting to produce detailed investment cast lattice structures. Fused filament fabrication is used to fabricate a pattern used as the mold for the investment casting of aluminium A356 alloy into high-conformity thin-ribbed (~ 0.6 mm thickness) scaffolds. X-ray micro-computed tomography (CT) is used to characterize macro- and meso-scale defects. Optical and scanning electron (SEM) microscopies are used to characterize the microstructure of the cast structures. Slight dimensional (macroscale) variations originate from the 3D printing of the pattern. At the mesoscale, the casting process introduces very fine (~ 3 µm) porosity, along with small numbers of (~ 25 µm) gas entrapment defects in the horizontal struts. At a microstructural level, both the (~ 70 μm) globular/dendritic grains and secondary phases show no significant variations across the lattices. This method is a promising alternative means for producing highly detailed non-stochastic metallic cellular lattices and offers scope for further improvement through refinement of filament fabrication.
“…Penerapan cooling slope pada saat penuangan cairan aluminium merupakan metode yang potensial untuk modifikasi struktur mikro. Pada penelitian sebelumnya telah disampaikan bahwa penggunaan pelat miring pada penuangan A356 mempengaruhi laju perpindahan panas, proses pengintian dan penghalusan butir [16]. Selain penghalusan butir, metode ini juga mempengaruhi pembentukan butir α-Al yang berbentuk spherical pada bahan alumunium A356 [17].…”
Alumunium (Al) A356 yang memiliki sifat mekanis yang baik telah secara luas dipergunakan di bidang teknik. Namun tidak dapat dihindari proses pengecoran ulang bahan Al termasuk A356 akan menurunkan sifat mekanis. Usaha perbaikan dan meminimalkan pengaruh tersebut telah dilakukan dengan berbagai cara diantaranya menggunakan cooling slope. Penelitian ini bertujuan untuk mengetahui sifat mekanis dan mikrostruktur pengecoran ulang aluminium A356 menggunakan metode cooling slope. Temperature penuangan 680oC dengan kemiringan 30˚, 45˚, 60˚ dan panjang pelat 80 cm dipasang sesaat sebelum cairan memasuki cetakan permanen. Observasi mikrostruktur menggunakan optical microscope (OM) memperlihatkan mikrostruktur tersusun dari primari Al dan partikel silikon. Variasi kemiringan pelat pada saat penuangan juga memengaruhi kehalusan mikrostruktur. Hasil pengujian kekerasan tertinggi 62 HB diperoleh pada variasi sudut tuang 30˚. Pengujian ketahanan aus dilakukan pada kondisi kering tanpa pelumas menggunakan metode pin on disc di mana diperoleh laju keausan paling rendah pada bahan dengan sudut kemiringan 30o dan tertinggi pada sudut 60o. Pada bagian lain, pengujian tarik dilakukan pada suhu kamar dengan hasil memperlihatkan kekuatan tarik maksimum 157 MPa untuk sampel dengan penuangan 30o.
“…Besides the shapes grain, the size is important to determine the mechanical properties. Further, this technique can be used to reduce the grain size aluminum alloy [6] through slurry formation before flows into the permanent mold.…”
Cooling slopes (CS) are the novel technique in the casting process, it suitable applied in the various alloys to modify the microstructure and mechanical properties. In the present work, the cooling slope has been designed and applied in the aluminumsilicon alloys. The effect of CS plate angle on microstructure and mechanical properties of aluminum alloy were investigated. The results suggested that the CS influenced the morphologies of materials which is correspond with the mechanical properties change.
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