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Zhu, B., Seifeddine, S., Jarfors, A. E. .., Leisner, P. & Zanella, C. (2019). A study of anodising behaviour of Al-Si components produced by rheocasting. Paper presented at 15th International conference on semi-solid processing of alloys and composites, October 22nd to 24th, 2018, Shenzhen, China. Solid State Phenomena, 285, 39-44
Open this publication in new window or tab >>A study of anodising behaviour of Al-Si components produced by rheocasting
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2019 (English)In: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 285, p. 39-44Article in journal (Refereed) Published
Abstract [en]

This paper aims to investigate the anodising behaviour of Al-Si components produced by rheocasting, to understand the effect of the surface liquid segregation (SLS) on the anodising response. The material investigated was EN AC 42000 Al-alloy with an addition of 150 ppm Sr. The component was rheocast and conventionally liquid cast for benchmarking. The RheoMetalTM process was used to prepare slurry and subsequently cast using a vertical pressure die casting machine. Prior to anodising, mechanical grinding was used as pre-treatment method for selected samples as comparison with components in the as-cast state. Anodising was performed on the components using a constant controlled voltage at 25 V, in 1 M H2SO4, at room temperature. The duration of anodising was varied from 30 mins to 120 mins to examine the relationship between oxide layer thickness and the anodising time. The oxide layer was investigated and characterised. The results demonstrated that the presence of the SLS layer, which was enriched with alloying elements, had a significant influence on the anodising behaviour of the cast component. The oxide layer thickness of the components produced by rheocasting and fully liquid casting was measured and compared. The relations between the oxide layer thickness and anodising time, as well as the casting methods are presented and discussed in this paper.

Place, publisher, year, edition, pages
Trans Tech Publications, 2019
Keywords
Anodising, Oxide Layer, Rheocasting
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-42630 (URN)10.4028/www.scientific.net/SSP.285.39 (DOI)2-s2.0-85059944290 (Scopus ID)
Conference
15th International conference on semi-solid processing of alloys and composites, October 22nd to 24th, 2018, Shenzhen, China
Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-31Bibliographically approved
Tarasov, V., Tan, H., Jarfors, A. E. .. & Seifeddine, S. (2019). Fuzzy logic-based modelling of yield strength of as-cast A356 alloy. Neural computing & applications (Print)
Open this publication in new window or tab >>Fuzzy logic-based modelling of yield strength of as-cast A356 alloy
2019 (English)In: Neural computing & applications (Print), ISSN 0941-0643, E-ISSN 1433-3058Article in journal (Refereed) Epub ahead of print
Abstract [en]

Uncertain and imprecise data are inherent to many domains, e.g. casting lightweight components. Fuzzy logic offers a way to handle such data, which makes it possible to create predictive models even with small and imprecise data sets. Modelling of cast components under fatigue load leads to understanding of material behaviour on component level. Such understanding is important for the design for minimum warranty risk and maximum weight reduction of lightweight cast components. This paper contributes with a fuzzy logic-based approach to model fatigue-related mechanical properties of as-cast components, which has not been fully addressed by the current research. Two fuzzy logic models are constructed to map yield strength to the chemical composition and the rate of solidification of castings for two A356 alloys. Artificial neural networks are created for the same data sets and then compared to the fuzzy logic approach. The comparison shows that although the neural networks yield similar prediction accuracy, they are less suitable for the domain because they are opaque models. The prediction errors exhibited by the fuzzy logic models are 3.53% for the model and 3.19% for the second, which is the same error level as reported in related work. An examination of prediction errors indicated that these are affected by parameters of the membership functions of the fuzzy logic model.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Fuzzy logic; Membership functions; Artificial neural networks; Prediction accuracy; Mechanical properties prediction; A356 alloy; Cast components
National Category
Materials Engineering Computer Engineering
Identifiers
urn:nbn:se:hj:diva-42912 (URN)10.1007/s00521-019-04056-5 (DOI)XYZ ()
Funder
Knowledge Foundation, 20170066
Available from: 2019-02-08 Created: 2019-02-08 Last updated: 2019-02-08
Bogdanoff, T., Dahle, A. K. & Seifeddine, S. (2018). Effect of Co and Ni Addition on the Microstructure and Mechanical Properties at Room and Elevated Temperature of an Al–7%Si Alloy. International Journal of metalcasting, 12(3), 434-440
Open this publication in new window or tab >>Effect of Co and Ni Addition on the Microstructure and Mechanical Properties at Room and Elevated Temperature of an Al–7%Si Alloy
2018 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 12, no 3, p. 434-440Article in journal (Refereed) Published
Abstract [en]

Increasing environmental demands are forcing the automotive industry to reduce vehicle emissions by producing more light-weight and fuel efficient vehicles. Al–Si alloys are commonly used in automotive applications because of excellent castability, high thermal conductivity, good wear properties and high strength-to-weight ratio. However, most of the aluminium alloys on the market exhibit significantly reduced strength at temperatures above 200 °C. This paper presents results of a study of the effects of Co and Ni in a hypoeutectic Al–Si alloy on microstructure and mechanical properties at room and elevated temperature. Tensile test specimens with microstructures comparable to those obtained in high-pressure die casting, i.e. SDAS ~ 10 µm, were produced by directional solidification in a Bridgman furnace. The results show an improvement in tensile properties up to 230 °C.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Al–Si alloy, mechanical properties, cobalt, nickel, elevated temperature
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37539 (URN)10.1007/s40962-017-0178-z (DOI)000436927100004 ()2-s2.0-85049356111 (Scopus ID)
Available from: 2017-10-03 Created: 2017-10-03 Last updated: 2019-02-05Bibliographically approved
Ceschini, L., Morri, A., Toschi, S., Bjurenstedt, A. & Seifeddine, S. (2018). Influence of sludge particles on the fatigue behavior of Al-Si-Cu secondary aluminium casting alloys. Metals, 8(4), Article ID 268.
Open this publication in new window or tab >>Influence of sludge particles on the fatigue behavior of Al-Si-Cu secondary aluminium casting alloys
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2018 (English)In: Metals, E-ISSN 2075-4701, Vol. 8, no 4, article id 268Article in journal (Refereed) Published
Abstract [en]

Al-Si-Cu alloys are the most widely used materials for high-pressure die casting processes. In such alloys, Fe content is generally high to avoid die soldering issues, but it is considered an impurity since it generates acicular intermetallics (β-Fe) which are detrimental to the mechanical behavior of the alloys. Mn and Cr may act as modifiers, leading to the formation of other Fe-bearing particles which are characterized by less harmful morphologies, and which tend to settle on the bottom of furnaces and crucibles (usually referred to as sludge). This work is aimed at evaluating the influence of sludge intermetallics on the fatigue behavior of A380 Al-Si-Cu alloy. Four alloys were produced by adding different Fe, Mn and Cr contents to A380 alloy; samples were remelted by directional solidification equipment to obtain a fixed secondary dendrite arm spacing (SDAS) value (~10 µm), then subjected to hot isostatic pressing (HIP). Rotating bending fatigue tests showed that, at room temperature, sludge particles play a detrimental role on fatigue behavior of T6 alloys, diminishing fatigue strength. At elevated temperatures (200◦C) and after overaging, the influence of sludge is less relevant, probably due to a softening of the α-Al matrix and a reduction of stress concentration related to Fe-bearing intermetallics.

Place, publisher, year, edition, pages
MDPI, 2018
Keywords
Al-Si-Cu alloys, Fatigue behavior, High pressure die casting, Intermetallics, Iron, Sludge
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-39389 (URN)10.3390/met8040268 (DOI)000434882800071 ()2-s2.0-85045762852 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2019-02-14Bibliographically approved
Wójcik, N. A., Jonson, B., Möncke, D., Palles, D., Kamitsos, E. I., Ghassemali, E., . . . Ali, S. (2018). Influence of synthesis conditions on glass formation, structure and thermal properties in the Na2O-CaO-P2O5 system doped with Si3N4 and Mg. Journal of Non-Crystalline Solids, 494, 66-77
Open this publication in new window or tab >>Influence of synthesis conditions on glass formation, structure and thermal properties in the Na2O-CaO-P2O5 system doped with Si3N4 and Mg
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2018 (English)In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 494, p. 66-77Article in journal (Refereed) Published
Abstract [en]

Oxynitride phosphate glasses and glass-ceramics were prepared using new synthesis routes for phosphate glasses. Materials were melted from pre-prepared glass samples in the system Na-Ca-P-O with addition of Mg and/or Si3N4 powders under different preparation conditions. The melting process was conducted at 1000–1500 °C either under air or nitrogen atmosphere to obtain materials with different nitrogen content. Their topography and structure were characterized by Confocal Microscopy, Scanning Electron Microscopy, X-ray powder diffraction and Raman and infrared spectroscopy techniques, while their chemical compositions were examined by Energy Dispersive X-ray spectroscopy (EDS). All materials prepared under nitrogen atmosphere were found to contain a relative low quantity of nitrogen and high amount of Nb leached from the crucible. The reaction with the Nb crucible was not previously observed for silicon-based oxynitride glasses. The synthesized materials form two groups: glasses and glass-ceramics. The first ones, were prepared under air and nitrogen atmospheres at temperatures up to 1400 °C, and were found to be amorphous and homogeneous. Raman and infrared spectroscopy measurements confirm the presence of amorphous phosphates in the synthesized materials. The samples of the second group were prepared at temperatures above 1400 °C and were found to be translucent and partially crystallized. They contain nanocrystallites of calcium and sodium phosphates including hydroxyapatite (HAp). The thermal properties of samples were studied by Differential Scanning Calorimetry (DSC). The obtained glass transition temperatures range from about 360 °C to 640 °C and exhibit high values for glass-ceramic materials. Stability is improved in the studied glass-ceramics because of the increased degree of network polymerization of the remaining glassy matrix. The approximate fragility index decreases two times for oxynitride materials compared to the primary glass. The synthesized new materials may be competitive to well-known bioactive phosphate glasses thanks to their improved stability by Mg, Si, N and Nb doping.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Sodium-calcium-phosphate glasses, Glass-ceramics, Oxynitride materials, Raman spectroscopy
National Category
Ceramics
Identifiers
urn:nbn:se:hj:diva-39381 (URN)10.1016/j.jnoncrysol.2018.04.055 (DOI)000436885100009 ()2-s2.0-85046826853 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2018-05-09 Created: 2018-05-09 Last updated: 2019-02-14Bibliographically approved
Zamani, M., Dini, H., Svoboda, A., Lindgren, L.-E., Seifeddine, S., Andersson, N.-E. & Jarfors, A. (2017). A dislocation density based constitutive model for as-cast Al-Si alloys: Effect of temperature and microstructure. International Journal of Mechanical Sciences, 121, 164-170
Open this publication in new window or tab >>A dislocation density based constitutive model for as-cast Al-Si alloys: Effect of temperature and microstructure
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2017 (English)In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 121, p. 164-170Article in journal (Refereed) Published
Abstract [en]

The flow stress of an as-cast Al-Si based alloy was modeled using a dislocation density based model. The developed dislocation density-based constitutive model describes the flow curve of the alloy with various microstructures at quite wide temperature range. Experimental data in the form of stress-strain curves for different strain rates ranging from 10−4 to 10−1 s−1 and temperatures ranging from ambient temperature up to 400 °C were used for model calibration. In order to model precisely the hardening and recovery process at elevated temperature, the interaction between vacancies and dissolved Si was included. The calibrated temperature dependent parameters for different microstructure were correlated to the metallurgical event of the material and validated. For the first time, a dislocation density based model was successfully developed for Al-Si cast alloys. The findings of this work expanded the knowledge on short strain tensile deformation behaviour of these type of alloys at different temperature, which is a critical element for conducting a reliable microstructural FE-simulation.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Aluminium cast alloy; Dislocation density; Eutectic phase; Si precipitation; Si solute; Vacancy concentration
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-27375 (URN)10.1016/j.ijmecsci.2017.01.003 (DOI)000395216300015 ()2-s2.0-85008703756 (Scopus ID)
Note

Finns som manuskript med titeln A Dislocation Density Based Yield Stress Model for as-cast EN AC-46000 Alloy i licentiatuppsats. 

Available from: 2015-06-22 Created: 2015-06-22 Last updated: 2017-12-12Bibliographically approved
Awe, S. A., Seifeddine, S., Jarfors, A. E. .., Lee, Y. C. & Dahle, A. (2017). Development of new Al-Cu-Si alloys for high temperature performance. Advanced Materials Letters, 8(6), 695-701
Open this publication in new window or tab >>Development of new Al-Cu-Si alloys for high temperature performance
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2017 (English)In: Advanced Materials Letters, ISSN 0976-3961, E-ISSN 0976-397X, Vol. 8, no 6, p. 695-701Article in journal (Refereed) Published
Abstract [en]

In a quest to develop new light metal alloys that can perform excellently at elevated-temperatures (from 300°C to 400°C), a ternary eutectic Al-Cu-Si alloy was exploited to gain a deeper understanding of the alloy system and its suitability for high temperature applications. The alloys studied, with chemical composition of Al-27%Cu-5%Si (by weight percent) with Ni addition in the range of 0 to 1.5%wt, were cast in a rapid solidification casting technique. The solidification characteristics of the alloy was studied using the Thermo-Calc software. Microstructures were characterized in a scanning electron microscope coupled with energy dispersive spectrometry (SEM-EDS). Finally, the elevated-temperatures tensile properties of the alloys were investigated. Comparing the microstructures and mechanical properties of these Al-Cu-Si(-Ni) alloys with conventional Al-Si alloy A319, the refined microstructure with dispersed Ni intermetallic particles formed in the as-cast Al-Cu-Si(-Ni) alloys deliver improved elevated temperature properties. In particular, the yield strength and ultimate tensile strength of the new alloy with 1.5% Ni at 400?C were observed to be 220% and 309% higher, respectively, than for conventional A319 alloy.

Place, publisher, year, edition, pages
VBRI Press, 2017
Keywords
Eutectic composite structure, casting, solidification, elevated-temperature performance, thermo-calc, tensile properties
National Category
Metallurgy and Metallic Materials Other Materials Engineering
Identifiers
urn:nbn:se:hj:diva-34093 (URN)10.5185/amlett (DOI)
Available from: 2016-11-28 Created: 2016-11-28 Last updated: 2018-02-08
Ghassemali, E., Riestra, M., Bogdanoff, T., Kumar, B. S. & Seifeddine, S. (2017). Hall-Petch Equation in a Hypoeutectic Al-Si Cast Alloy: Grain Size vs. Secondary Dendrite Arm Spacing. In: Procedia Engineering: . Paper presented at International Conference on the Technology of Plasticity, ICTP 2017; Hucisko; United Kingdom; 17 September 2017 through 22 September 2017 (pp. 19-24). Elsevier, 207
Open this publication in new window or tab >>Hall-Petch Equation in a Hypoeutectic Al-Si Cast Alloy: Grain Size vs. Secondary Dendrite Arm Spacing
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2017 (English)In: Procedia Engineering, Elsevier, 2017, Vol. 207, p. 19-24Conference paper, Published paper (Refereed)
Abstract [en]

The Al-Si cast alloy family is widely used in the production of complex castings for various applications and known for its very good castability and high strength-to-weight ratio. However, early cracking under tensile loading is sometimes a limiting factor. Among other parameters, it is yet controversial whether grain boundaries are dominant strengthening factor in cast alloys, instead of dendrite/eutectic boundaries. This study presents the effect of secondary dendrite arm spacing (SDAS) and grain size on crack initiation and propagation of Al-Si cast alloys under tensile loading. The Al-10Si (wt.%) alloy with modified Si morphology was cast using inoculants (Al-5Ti-B master alloy) under different cooling rates to obtain a range of grain sizes (from below 138 μm to above 300 μm) and SDAS (6, 15 and 35 μm). Conventional tensile test as well as in-situ tensile test in a scanning electron microscope, equipped with an electron backscatter diffraction (EBSD) was carried out to understand the deformation mechanisms of the alloy. Observation of slip bands within the dendrites showed that in modified Si structure, the interdendritic (eutectic) area takes more portion of the strain during plastic deformation. Besides, only a few cracks were initiated at the grain boundaries; they were mostly initiated from dendrite/eutectic interface. All cracks propagated trans-granularly. Hall-Petch calculations also showed a strong relationship between SDAS and flow stress of the cast alloy. Although statistically correct, there was no physically meaningful relationship between the grain size and the flow stress. Nevertheless, formation of identical slip bands in each grain could be an evidence for the marginal effect of the grain size on the overall strength development of the alloy. Consequently, among other effects, the combinational dominant effect of SDAS and modest effect of grain size shall be considered for modification of the Hall-Petch equation for precise prediction of mechanical properties of cast alloys.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Procedia Engineering, ISSN 1877-7058 ; 207
Keywords
Aluminum, Aluminum alloys, Aluminum compounds, Cracks, Grain boundaries, Grain size and shape, High strength alloys, Plastic flow, Plasticity, Scanning electron microscopy, Silicon, Tensile stress, Tensile testing, Titanium alloys, Titanium compounds, Cast alloys, Crack initiation and propagation, Cracking mechanisms, EBSD, Electron back scatter diffraction, Hall-petch, Prediction of mechanical properties, Secondary dendrite arm spacing, Silicon alloys
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38004 (URN)10.1016/j.proeng.2017.10.731 (DOI)XYZ ()2-s2.0-85036643961 (Scopus ID)
Conference
International Conference on the Technology of Plasticity, ICTP 2017; Hucisko; United Kingdom; 17 September 2017 through 22 September 2017
Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2018-06-11Bibliographically approved
Ali, S., Bogdanoff, T., Seifeddine, S. & Jonson, B. (2017). Hardness, elastic modulus and refractive index of oxynitride glasses prepared from woody biofuel ashes. European Journal of Glass Science and Techology. Part B. Physics and Chemistry of Glasses, 58(6), 231-236
Open this publication in new window or tab >>Hardness, elastic modulus and refractive index of oxynitride glasses prepared from woody biofuel ashes
2017 (English)In: European Journal of Glass Science and Techology. Part B. Physics and Chemistry of Glasses, ISSN 1753-3562, Vol. 58, no 6, p. 231-236Article in journal (Refereed) Published
Abstract [en]

This paper reports the hardness, elastic modulus and refractive index values of the oxynitride glasses prepared from woody biofuel ashes. The glasses were prepared in nitrogen atmosphere at 1350-1500°C with addition of Ca metal as a precursor to the extra addition of this modifier. The glasses were homogenous, but appeared translucent grey to black. They contained up to 23 eq% of Ca and 5 eq% of N. The glass densities vary slightly between 2·76 to 2·92 g/cm3. The molar volume and compactness values vary between 8·01 cm3/mol to 8·31 cm3/mol and 0·446 to 0·462 respectively. Mechanical properties like hardness and reduced elastic modulus show values, up to 10 and 105 GPa, respectively. These properties are strongly correlated with the amount of N in the glass. The refractive index (1·54-1·75) increases with increasing N and Ca contents.

Place, publisher, year, edition, pages
Society of Glass Technology, 2017
Keywords
Biofuels, Calcium, Elastic moduli, Glass, Hardness, Nitrides, Biofuel ashes, Glass density, Nitrogen atmospheres, Oxynitride glass, Reduced elastic modulus, Refractive index
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38297 (URN)10.13036/17533562.58.6.039 (DOI)000415784300001 ()2-s2.0-85033780200 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-12-27 Created: 2017-12-27 Last updated: 2018-09-11Bibliographically approved
Bjurenstedt, A., Casari, D., Seifeddine, S., Mathiesen, R. H. & Dahle, A. K. (2017). In-situ study of morphology and growth of primary α-Al(FeMnCr)Si intermetallics in an Al-Si alloy. Acta Materialia, 130, 1-9
Open this publication in new window or tab >>In-situ study of morphology and growth of primary α-Al(FeMnCr)Si intermetallics in an Al-Si alloy
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2017 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 130, p. 1-9Article in journal (Refereed) Published
Abstract [en]

Morphology and growth of primary α-Al(FeMnCr)Si intermetallics have been studied in-situ during solidification of a commercial secondary aluminum alloy employing X-radiographic imaging combined with deep-etching. The α-Al(FeMnCr)Si intermetallics were found to nucleate primarily on surface oxides, and the continued growth yielded both rhombic dodecahedrons and elongated rod-like morphologies. Both morphologies were observed as hopper and massive types, where the hopper intermetallics had the higher growth rates. The growth rate, which determines the type, appears to be linked to nucleation frequency; higher nucleation frequency promoted massive types and lower nucleation frequency promoted hopper intermetallics. 

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Aluminum, Casting, Crystal growth, Intermetallics, Primary α-Al(FeMnCr)Si, Aluminum alloys, Hoppers, Morphology, Nucleation, Silicon, Silicon alloys, Deep etching, In-Situ Study, Nucleation frequencies, Rhombic dodecahedron, Rod-like morphology, Secondary aluminum, Surface oxide, X-radiographic imaging
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-35343 (URN)10.1016/j.actamat.2017.03.026 (DOI)000401388700001 ()2-s2.0-85015790499 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-04-10 Created: 2017-04-10 Last updated: 2017-08-21Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-6481-5530

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