Non-Conventional Sintered Aluminium Powder Alloys

Sercombe, Timothy Barry (1998). Non-Conventional Sintered Aluminium Powder Alloys PhD Thesis, Department of Mining, Minerals and Materials Engineering, The University of Queensland.

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A00_19990009.pdf Full thesis (Author version) application/pdf 2.15MB 1056
appendix.pdf appendix.pdf application/pdf 2.15MB 114
chapter1.pdf chapter1.pdf application/pdf 2.15MB 106
chapter2.pdf chapter2.pdf application/pdf 2.15MB 287
chapter3.pdf chapter3.pdf application/pdf 2.15MB 119
chapter4.pdf chapter4.pdf application/pdf 2.15MB 99
chapter5.pdf chapter5.pdf application/pdf 2.15MB 73
chapter6.pdf chapter6.pdf application/pdf 2.15MB 83
chapter7.pdf chapter7.pdf application/pdf 2.15MB 102
chapter8.pdf chapter8.pdf application/pdf 2.15MB 145
chapter9.pdf chapter9.pdf application/pdf 2.15MB 68
front.pdf front.pdf application/pdf 2.15MB 304
references.pdf references.pdf application/pdf 57KB 1077
Author Sercombe, Timothy Barry
Thesis Title Non-Conventional Sintered Aluminium Powder Alloys
School, Centre or Institute Department of Mining, Minerals and Materials Engineering
Institution The University of Queensland
Publication date 1998
Thesis type PhD Thesis
Open Access Status Other
Supervisor Graham Schaffer
Subjects 291403 Alloy Materials
Abstract/Summary The aim of this thesis was to improve the properties of pressed and sintered aluminium powder alloys. This improvement was to be achieved using two methods. The first method involved the selection of an alloy system using binary aluminium phase diagrams and a knowledge of the phase diagram characteristics of ideal sintering systems. The second approach involved the judicious use of selected trace element additions to modify the sintering characteristics of aluminium and its alloys. A trace amount of magnesium was found to be critical to the sintering of aluminium powder due to its disrupting effect on the tenacious oxide layer covering the powder particles. The critical amount of Mg required to optimise both density and mechanical properties is dependent on the specific volume of oxide and the therefore particle size. The optimum concentration is 0.1-1.0wt% Mg. The Al-Sn phase diagram exhibits many of the characteristics of an ideal sintering system. Unsurprisingly, Sn was found to be an extremely efficient sintering aid, but only in the presence of Mg. Near full density parts were produced using an Al-8Sn-0.15Mg alloy in short sintering times (30 minutes). Additionally, as-sintered ductilities exceeding 20% were achieved using an Al-2Sn-0.15Mg alloy. Alloys based on the Al-Sn-Mg system lend themselves to sintering without compaction and therefore freeformed Al-Sn-Mg alloys have been produced and sintered to near full density from a starting density of ~50%. Trace amounts of Sn (Pb, In, Bi, or Sb) enhance the sintering response of an Al-4Cu-0.15Mg alloy via a vacancy binding mechanism. A similar mechanism suppresses natural ageing and stimulates artificial ageing when trace amounts of Sn are added to this alloy. A Sn-modified 2XXX series alloy has also been produced with mechanical properties nearly 20% above current commercial alloys. Along with the addition of 0.1wt%Sn, this improvement required an alteration to the solution treatment cycle which allowed the use of a higher sintering temperature without the formation of large amounts of boundary phase.
Keyword sintering aluminium
trace element effects

Document type: Thesis
Collection: UQ Theses (RHD) - Open Access
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Created: Fri, 21 Nov 2008, 21:04:41 EST