Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Effect of Material Inhomogeneity on Thermal Performance of a Rheocast Aluminum Heatsink for Electronics Cooling
Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. (CompCast)ORCID iD: 0000-0001-6755-2123
Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing - Surface technology. (CompCast)
Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. (RheoCom)ORCID iD: 0000-0002-0101-0062
Jönköping University, School of Engineering, JTH. Research area Materials and manufacturing – Casting. RheoMetal. (CompCast)
2016 (English)In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 25, no 6, 2116-2127 p.Article 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. Vol. 25, no 6, 2116-2127 p.
Keyword [en]
computer simulation, heatsink, microstructural inhomogeneity, rheocasting, thermal conductivity, thermal management
National Category
Metallurgy and Metallic Materials
Identifiers
URN: urn:nbn:se:hj:diva-29918DOI: 10.1007/s11665-016-2102-8OAI: oai:DiVA.org:hj-29918DiVA: diva2:928618
Projects
CompCast
Funder
Knowledge Foundation, 20100203
Available from: 2016-05-16 Created: 2016-05-16 Last updated: 2017-05-09Bibliographically approved
In thesis
1. Rheocasting of aluminium alloys: Process and components characteristics
Open this publication in new window or tab >>Rheocasting of aluminium alloys: Process and components characteristics
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Semi-Solid Metal (SSM) casting is a promising technology offering an opportunity to manufacture net-shape, complex geometry metal components in a single operation. However, the absence of foundry guidelines and limited design data for SSM casting makes it challenging to predict the performance of both process and components. The objective of this research was to develop and offer new solutions to material processing-related issues in the electronics industry. By investigating the opportunities afforded by the recently developed RheoMetalTM rheocasting process, a better understanding of the critical factors needed for an effective manufacturing process and optimised component characteristics was achieved.

A study of the evolution of microstructure at different stages of the RheoMetalTM process demonstrated the influence of multistage solidification on the microstructural characteristics of the rheocast components. The microstructure of a slurry consists of the solute-lean and coarse globular α-Al particles with a uniform distribution of alloying elements, suspended in the liquid matrix. Additional solute-rich α-Al particles were identified as being a consequence of discrete nucleation events taking place after the initial slurry production. In the final components, macrosegregation was observed in the form of variations in the ratio of solute-lean coarse globular α-Al particles and solute-rich fine α-Al particles in both longitudinal and transverse directions.

The relation between microstructural characteristics and material properties was established by determination of the local properties of a rheocast component. The fracture of a rheocast telecom component was strongly affected by microstructural inhomogeneity. In particular, macrosegregation in the form of liquid surface segregation bands and sub-surface pore bands strongly affected the fracture behaviour. Thermal conductivity measurements revealed that regions of the component with a high amount of solute-lean globular α-Al particles showed higher thermal conductivity. The effect of the local variation in thermal conductivity on the thermal performance of a large rheocast heatsink was evaluated by simulation. The results clearly show the importance of considering material inhomogeneity when creating a robust component design.

Place, publisher, year, edition, pages
Jönköping: Jönköping University, School of Engineering, 2016. 45 p.
Keyword
Rheocasting, aluminium alloy, RheoMetal(TM) process, microstructural characteristics, component properties and performance, robust design process
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-31428 (URN)978-91-87289-16-3 (ISBN)
Public defence
2016-09-23, E1405, School of Engineering, Jönköping, 10:00 (English)
Opponent
Supervisors
Funder
Knowledge Foundation
Available from: 2016-08-22 Created: 2016-08-22 Last updated: 2016-08-22Bibliographically approved

Open Access in DiVA

fulltext(5957 kB)1 downloads
File information
File name FULLTEXT02.pdfFile size 5957 kBChecksum SHA-512
525772ac4f7ce2cfc341dc1ca5bcfb10636eada6b3cb94709084e1ff59e8f83741e8a07c2b9266d05dcf398ab2b49ce52ce1deddbb2b2f6190ae986636ef4bf0
Type fulltextMimetype application/pdf

Other links

Publisher's full texthttp://link.springer.com/article/10.1007/s11665-016-2102-8

Search in DiVA

By author/editor
Payandeh, MostafaBelov, IljaJarfors, Anders E.WWessén, Magnus
By organisation
JTH. Research area Materials and manufacturing – CastingJTH. Research area Materials and manufacturing - Surface technology
In the same journal
Journal of materials engineering and performance (Print)
Metallurgy and Metallic Materials

Search outside of DiVA

GoogleGoogle Scholar
Total: 1 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 275 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf