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Wessén, Magnus
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Publications (10 of 79) Show all publications
Payandeh, M., Sabzevar, M. H., Jarfors, A. E. .. & Wessén, M. (2017). Solidification and re-melting phenomena during slurry preparation using the RheoMetal™ process. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 48(6)
Open this publication in new window or tab >>Solidification and re-melting phenomena during slurry preparation using the RheoMetal™ process
2017 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 6Article in journal (Refereed) Published
Abstract [en]

The melting sequence of the enthalpy exchange material (EEM) and formation of a slurry in the RheoMetal™ process was investigated. The EEM was extracted and quenched, together with a portion of the slurry at different processing times before complete melting. The EEM initially increased in size/diameter due to melt freezing onto its surface, forming a freeze-on layer. The initial growth of this layer was followed by a period of a constant diameter of the EEM with subsequent melting and decrease of diameter. Microstructural characterization of the size and morphology of different phases in the EEM and in the freeze-on layer was made. Dendritic equiaxed grains and eutectic regions containing Si particles and Cu-bearing particles and Fe-rich particles were observed in the as-cast EEM. The freeze-on layer consisted of dendritic aluminum tilted by about 30 deg in the upstream direction, caused by the rotation of the EEM. Energy dispersion spectroscopy analysis showed that the freeze-on layer had a composition corresponding to an alloy with higher melting point than the EEM and thus shielding the EEM from the surrounding melt. Microstructural changes in the EEM showed that temperature rapidly increased to 768 K (495 °C), indicated by incipient melting of the lowest temperature melting eutectic in triple junction grain boundary regions with Al2Cu and Al5Mg8Si6Cu2 phases present. As the EEM temperature increased further the binary Al-Si eutectic started to melt to form a region of a fully developed coherent mushy state. Experimental results and a thermal model indicated that as the dendrites spheroidized near to the interface at the EEM/freeze-on layer reached a mushy state with 25 pct solid fraction, coherency was lost and disintegration of the freeze-on layer took place. Subsequently, in the absence of the shielding effect from the freeze-on Layer, the EEM continued to disintegrate with a coherency limit of a solid fraction estimated to be 50 pct.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37097 (URN)10.1007/s11663-017-1061-2 (DOI)000415806100004 ()2-s2.0-85028010241 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-08-30 Created: 2017-08-30 Last updated: 2018-09-19Bibliographically approved
Esmaily, M., Mortazavi, N., Svensson, J.-E., Halvarsson, M., Wessén, M., Johansson, L.-G. & Jarfors, A. E. .. (2016). A new semi-solid casting technique for fabricating SiC-reinforced Mg alloys matrix composites. Composites Part B: Engineering, 94, 176-189
Open this publication in new window or tab >>A new semi-solid casting technique for fabricating SiC-reinforced Mg alloys matrix composites
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2016 (English)In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 94, p. 176-189Article in journal (Refereed) Published
Abstract [en]

The capability of the newly developed rheocasting (RC) technique in combination with the RheoMetal process for producing SiC particulate-reinforced AM50 and AZ91D matrix composites (Mg-based MMCs) was investigated. The quality of the MMCs was studied by analyzing the fraction of casting pores, number density of SiC clusters and the uniformity of SiC particles. Solid fraction, particle size and oxidation of SiC particles had strong impacts on the overall quality of the MMCs. The MMCs produced by 40% solid fraction and oxidized micron-sized SiC particles exhibited an excellent casting quality. A low-quality MMC was obtained when non-oxidized sub-micron sized SiC particles were employed. The results showed the formation of various types intermetallic particles and carbides such as MgO, Mg2Si, Al2MgC2, Mg2C3, Al4C3 as the interfacial reaction products of SiC/Mg alloy’s melts. Mg hydride (α-MgH2) was also identified in inter-dendritic regions of the MMCs for the first time.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Metal-matrix composites (MMCs), Microstructure, Magnesium alloys, Casting
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-29719 (URN)10.1016/j.compositesb.2016.02.019 (DOI)000376052600018 ()2-s2.0-84962734666 (Scopus ID)
Available from: 2016-04-06 Created: 2016-04-06 Last updated: 2017-11-30Bibliographically approved
Belov, I., Payandeh, M., Leisner, P., Jarfors, A. E. .. & Wessen, M. (2016). Effect of fillets on heat transfer in a rheocast aluminium heatsink. In: 2016 17th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE): . Paper presented at 17th International Conference IEEE EuroSimE, Montpellier, April 17-20, 2016.. IEEE
Open this publication in new window or tab >>Effect of fillets on heat transfer in a rheocast aluminium heatsink
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2016 (English)In: 2016 17th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), IEEE, 2016Conference paper, Published paper (Refereed)
Abstract [en]

The effect of fillets formed between the base and plate fins of rheocast aluminium heatsinks on the thermal resistance of the heatsinks has been quantified by simulation. Simulation methodology, including sequential optimization has been developed in order to determine hotspot distributions where the fillets have the maximum effect. Combination of different fillet dimensions with various base thickness levels and aluminium alloys having inhomogeneous thermal conductivity have been investigated. For the studied cases, the effect of fillets on heatsink thermal resistance differs from negligible to 6%. The results would guide thermal designers on contribution of fillets to the heat transfer in multi-fin heatsinks for natural convection.

Place, publisher, year, edition, pages
IEEE, 2016
Keywords
Heating, Heat transfer, Metals, Conductivity, Temperature measurement, Thermal resistance
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-28920 (URN)10.1109/EuroSimE.2016.7463320 (DOI)000381743700028 ()2-s2.0-84974569543 (Scopus ID)978-1-5090-2106-2 (ISBN)
Conference
17th International Conference IEEE EuroSimE, Montpellier, April 17-20, 2016.
Available from: 2016-01-08 Created: 2016-01-08 Last updated: 2018-09-12Bibliographically approved
Payandeh, M., Belov, I., Jarfors, A. E. . & Wessén, M. (2016). Effect of Material Inhomogeneity on Thermal Performance of a Rheocast Aluminum Heatsink for Electronics Cooling. Journal of materials engineering and performance (Print), 25(6), 2116-2127
Open this publication in new window or tab >>Effect of Material Inhomogeneity on Thermal Performance of a Rheocast Aluminum Heatsink for Electronics Cooling
2016 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 25, no 6, p. 2116-2127Article in journal (Refereed) Published
Abstract [en]

The relation between microstructural inhomogeneity and thermal conductivity of a rheocast componentmanufactured from two different aluminum alloys was investigated. The formation of two different primarya-Al particles was observed and related to multistage solidification process during slurry preparationand die cavity filling process. The microstructural inhomogeneity of the component was quantified as thefraction of a1-Al particles in the primary Al phase. A high fraction of coarse solute-lean a1-Al particles inthe primary Al phase caused a higher thermal conductivity of the component in the near-to-gate region. Avariation in thermal conductivity through the rheocast component of 10% was discovered. The effect of aninhomogeneous temperature-dependent thermal conductivity on the thermal performance of a largerheocast heatsink for electronics cooling in an operation environment was studied by means of simulation.Design guidelines were developed to account for the thermal performance of heatsinks with inhomogeneousthermal conductivity, as caused by the rheocasting process. Under the modeling assumptions, the simulationresults showed over 2.5% improvement in heatsink thermal resistance when the higher conductivity nearto-gate region was located at the top of the heatsink. Assuming homogeneous thermo-physical properties ina rheocast heatsink may lead to greater than 3.5% error in the estimation of maximum thermal resistanceof the heatsink. The variation in thermal conductivity within a large rheocast heatsink was found to beimportant for obtaining of a robust component design.

Place, publisher, year, edition, pages
Springer, 2016
Keywords
computer simulation, heatsink, microstructural inhomogeneity, rheocasting, thermal conductivity, thermal management
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-29918 (URN)10.1007/s11665-016-2102-8 (DOI)000376449100003 ()2-s2.0-84966495065 (Scopus ID)
Projects
CompCast
Funder
Knowledge Foundation, 20100203
Available from: 2016-05-16 Created: 2016-05-16 Last updated: 2018-10-16Bibliographically approved
Payandeh, M., Sjölander, E., Jarfors, A. & Wessén, M. (2016). Influence of microstructure and heat treatment on thermal conductivity of rheocast and liquid die cast Al-6Si-2Cu-Zn alloy. International Journal of Cast Metals Research, 29(4), 202-213
Open this publication in new window or tab >>Influence of microstructure and heat treatment on thermal conductivity of rheocast and liquid die cast Al-6Si-2Cu-Zn alloy
2016 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 4, p. 202-213Article in journal (Refereed) Published
Abstract [en]

Thermal conductivity of a rheocast component made from Stenal Rheo1 (Al-6Si-2Cu-Zn) alloy was investigated in as-cast, T5 and T6 conditions. The thermal conductivity measurement in different locations showed variation of this property throughout the rheocast component. The results of microstructural investigation revealed that the ratio of solute-lean α1-Al particles formed during slurry preparation to fine solute-rich α2-Al particles formed during secondary solidification had significant influence on thermal conductivity. The reduced amount of solutes in the α1-Al particles was determined as the root cause of higher thermal conductivity. A linear relation between the fraction of precipitates and the increase in thermal conductivity was obtained and silicon in solid solution is shown to have a dominant influence. As silicon was precipitated during the heat treatment, thermal conductivity increased. For an optimal combination of thermal and mechanical properties, it is therefore important to use an ageing temperature above the temperature of Si precipitation.

Keywords
Aluminium alloy, High-pressure die casting, Microstructure characteristics, Rheocasting, Thermal conductivity, Aluminum, Aluminum alloys, Copper alloys, Die casting, Heat treatment, Microstructure, Silicon, Thermal conductivity of solids, Zinc, Ageing temperature, High pressure die casting, Microstructural investigation, Optimal combination, Si precipitations, Thermal and mechanical properties, Thermal conductivity measurements
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-31227 (URN)10.1080/13640461.2015.1125990 (DOI)000378146800003 ()2-s2.0-84978732257 (Scopus ID)
Available from: 2016-08-11 Created: 2016-08-11 Last updated: 2017-11-28Bibliographically approved
Esmaily, M., Mortazavi, N., Svensson, J.-E., Halvarsson, M., Jarfors, A. E. .., Wessén, M., . . . Johansson, L.-G. (2016). On the microstructure and corrosion behavior of AZ91/SiC composites produced by rheocasting. Materials Chemistry and Physics, 180, 29-37
Open this publication in new window or tab >>On the microstructure and corrosion behavior of AZ91/SiC composites produced by rheocasting
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2016 (English)In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 180, p. 29-37Article in journal (Refereed) Published
Abstract [en]

The corrosion behavior of magnesium-aluminum (Mg-Al) alloy AM50 produced by a rheocasting (RC) technique was examined in the presence and absence of CO2 at three temperatures -4, 4 and 22 degrees C. The slurry preparation in the RC material was performed with the newly developed RheoMetal process. For reference, 99.97% Mg was included in the corrosion exposures. The influence of the microstructure on the atmospheric corrosion of alloy AM50 produced by RC and high pressure die casting (HPDC) was investigated. The RC AM50 alloy showed better corrosion resistance than HPDC AM50 in all the exposure environments studied. For both materials, there was a strong positive correlation between temperature and the atmospheric corrosion rate. The superior atmospheric corrosion behavior of RC AM50 compared to HPDC AM50 is carefully discussed in relation to differences in the as-cast microstructure. This study demonstrates that producing the alloy AM50 by this type of RC technique opens the door to Mg-Al alloys as a promising candidate for various applications where corrosion resistance is of importance.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Magnesium alloy, Composite materials, Microstructure, Corrosion
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-34781 (URN)10.1016/j.matchemphys.2016.05.016 (DOI)000380077600005 ()2-s2.0-84969922473 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-01-18 Created: 2017-01-18 Last updated: 2018-06-08Bibliographically approved
Payandeh, M., Sabzevar, M. H., Jarfors, A. E. .. & Wessén, M. (2016). Solidification and re-melting phenomena during the slurry preparation stage using the RheoMetalTM process. Jönköping: Jönköping University, School of Engineering
Open this publication in new window or tab >>Solidification and re-melting phenomena during the slurry preparation stage using the RheoMetalTM process
2016 (English)Report (Other academic)
Abstract [en]

The melting sequence of the Enthalpy Exchange Material (EEM) and formation of slurry in the RheoMetalTM process was investigated. The EEM was extracted, together with a portion of the slurry at different times before complete melting, and quenched. The EEM initially increased in size due to melt freezing onto its surface, forming a freeze-on layer. The initial growth of this layer was followed by a constant diameter of the EEM and thereafter subsequent melting. Microstructural characterization of the size and morphology of different phases in the EEM and the freeze-on layer was made. Dendritic equiaxed grains and eutectic regions containing Si particles and Cu-bearing particles were observed in the as-cast EEM. The freeze-on layer consisted of dendritic aluminum slightly tilted by about 30° toward the upstream direction, caused by the rotation of the EEM. Energy Dispersion Spectroscopy analysis showed that the freeze-on layer had a composition corresponding to a higher melting point than the EEM.

Microstructural investigation of the EEM showed that the temperature rapidly increased to 495 ºC, causing incipient melting of Al2Cu and Al5Mg8Si6Cu2 phases in grain boundary regions. Following the incipient melting, the temperature in the EEM increased further and binary Al-Si eutectic started to melt to form a region of a fully developed coherent mushy state. Experimental results and a thermal model indicated that as the dendrites spheroidized and the interface at the EEM/freeze-on layer reached a mushy state with 25% solid fraction, coherency was lost and disintegration of the freeze-on layer took place. Subsequently, in the absence of the shielding effect from the freeze-on Layer, the EEM disintegrates at a higher solid fraction, estimated to be 50%. The fast and complex slurry generation in the RheoMetalTM process is a hybrid process with both rheocasting and thixocasting elements in the process.

Place, publisher, year, edition, pages
Jönköping: Jönköping University, School of Engineering, 2016. p. 21
Series
JTH research report, ISSN 1404-0018 ; 5
Keywords
Rheocasting, RheoMetal(TM) process, Slurry fabrication, Solidification, Melting, Heat Transfer Model
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-31430 (URN)
Available from: 2016-08-22 Created: 2016-08-22 Last updated: 2016-08-22Bibliographically approved
Payandeh, M., Jarfors, A. E. W. & Wessén, M. (2016). Solidification sequence and evolution of microstructure during rheocasting of four Al-Si-Mg-Fe alloys with Low Si content. Metallurgical and Materials Transactions. A, 47(3), 1215-1228
Open this publication in new window or tab >>Solidification sequence and evolution of microstructure during rheocasting of four Al-Si-Mg-Fe alloys with Low Si content
2016 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 47, no 3, p. 1215-1228Article in journal (Refereed) Published
Abstract [en]

Four Al-Si-Mg-Fe alloys with Si contents varying from 1.6 to 4.5 wt pct were rheocast, using the RheoMetal™ process to prepare slurry and cast in a vertical high-pressure die casting machine. Particle size and Si concentration in the α-Al particles in the slurry and in the as-rheocast component were investigated. A uniform distribution of Si in the globular α 1-Al particles was achieved in the slurry. In the rheocast samples, measurement of the α 1-Al particles showed that these particles did not increase significantly in size during pouring and secondary solidification. The two additional α-Al particles types, α 2-Al particles and α 3-Al particles, were identified as being a result of two discrete nucleation events taking place after slurry production. The Si concentration in the α 2-Al and α 3-Al particles indicated that the larger α 2-Al particles precipitated before the α 3-Al particles. In addition, in the as-rheocast condition, the Si distribution inside the α 1-Al particles showed three distinct zones; an unaffected zone, a transition zone, and in some cases the start of a dendritic/cellular zone. The phenomenon of dendritic growth of globular α 1-Al particles during secondary solidification occurred concomitantly with the final eutectic reaction and increased with increasing amount of the Al-Si eutectic phase.

Place, publisher, year, edition, pages
Springer, 2016
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-26312 (URN)10.1007/s11661-015-3290-9 (DOI)000371308200022 ()2-s2.0-84951985830 (Scopus ID)
Note

Submitted (and included in licentiate thesis) under the name: Solidification sequence and evolution of microstructure during rheocasting of Al-Si-Mg-Fe alloys with low Si content

Available from: 2015-04-08 Created: 2015-04-08 Last updated: 2018-06-08Bibliographically approved
Payandeh, M., Jarfors, A. E. .. & Wessén, M. (2016). The effect of microstructural inhomogeneity on thermal diffusivity in a rheocast component. Paper presented at High Tech Die Casting 2016, Venice, 22-23 June, 2016.. La Metallurgia Italiana, 108(6), 57-60
Open this publication in new window or tab >>The effect of microstructural inhomogeneity on thermal diffusivity in a rheocast component
2016 (English)In: La Metallurgia Italiana, ISSN 0026-0843, Vol. 108, no 6, p. 57-60Article in journal (Refereed) Published
Abstract [en]

The relationship between microstructural characteristics and thermal diffusivity of a rheocast component was investigated for two Al-Si-Mg-Fe alloys with low Si contents. The microstructural investigation of the components clearly depicted the formation of coarse solute-lean globular α1-Al particles during the slurry fabrication process and fine solute-rich α2-Al and α3-Al particles during the secondary solidification in the die cavity. The microstructural characterization was quantified based on the amount of α1-Al particles in different locations of the component. The result clearly revealed a presence of both longitudinal and transverse macrosegregation of solute-lean α1-Al particles in the rheocast component. The study of thermal diffusivity and hardness revealed that the regions of the component with a high fraction of α1-Al particles had a higher thermal diffusivity but a lower hardness. Silicon in the solid solution was observed to be a critical factor in reducing the thermal diffusivity. The comparison between the effect of longitudinal and transverse segregation on thermal diffusivity showed that the transverse segregation had a stronger impact.

Place, publisher, year, edition, pages
Milano: Associazione Italiana di Metallurgia, 2016
Keywords
SSM casting, Aluminium Alloys, Inhomogeneity, Microstructure, Hardness, Thermal Diffusivity
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-30581 (URN)2-s2.0-85009384672 (Scopus ID)
Conference
High Tech Die Casting 2016, Venice, 22-23 June, 2016.
Projects
CompCastRheoCom
Funder
Knowledge Foundation, 20100280
Available from: 2016-06-16 Created: 2016-06-16 Last updated: 2018-10-16Bibliographically approved
Esmaily, M., Mortazavi, S. N., Svensson, J.-E., Halvarsson, M., Blücher, D. B., Jarfors, A. E. .., . . . Johansson, L.-G. (2015). Atmospheric Corrosion of Mg Alloy AZ91D Fabricated by aSemi-Solid Casting Technique: The Influence of Microstructure. Journal of the Electrochemical Society, 162(7), C311-C321
Open this publication in new window or tab >>Atmospheric Corrosion of Mg Alloy AZ91D Fabricated by aSemi-Solid Casting Technique: The Influence of Microstructure
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2015 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 162, no 7, p. C311-C321Article in journal (Refereed) Published
Abstract [en]

The atmospheric corrosion behavior of alloy AZ91D produced by a semi-solid metal (SSM) technique and by conventional high pressure die casting (HPDC) was investigated for up to 1176 hours in the laboratory. Alloy AZ91D in the SSM state was fabricated using a rheocasting (RC) technique in which the slurry was prepared by the RheoMetal process. Exposures were performed in 95% RH air at 22 and 4 degrees C. The RC alloy AZ91D exhibited significantly better corrosion resistance than the HPDC material at two temperatures studied. The effect of casting technology on corrosion is explained in terms of the microstructural differences between the materials. For example, the larger number density of cathodic beta phase particles in the HPDC material initially causes relatively rapid corrosion compared to the RC material. During later stages of corrosion, the more network-like beta phase particles in the RC alloy act as a corrosion barrier, further improving the relative corrosion resistance of the RC material.

Keywords
Alloys, Atmospheric corrosion, Billets (metal bars), Corrosion, Corrosion resistance, Die casting, Atmospheric corrosion behavior, Casting technology, Corrosion barriers, High pressure die casting, Micro-structural, Rapid corrosion, Semi solid casting, Semi solid metals
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-28888 (URN)10.1149/2.0341507jes (DOI)000355643700050 ()2-s2.0-84929464342 (Scopus ID)
Available from: 2016-01-07 Created: 2016-01-07 Last updated: 2017-12-01Bibliographically approved
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