Agglomeration and bending of equiaxed crystals during solidification of hypoeutectic Al and Mg alloys

Otarawanna, S., Gourlay, C. M., Laukli, H. I. and Dahle, A. K. (2010) Agglomeration and bending of equiaxed crystals during solidification of hypoeutectic Al and Mg alloys. Acta Materialia, 58 1: 261-271.


Author Otarawanna, S.
Gourlay, C. M.
Laukli, H. I.
Dahle, A. K.
Title Agglomeration and bending of equiaxed crystals during solidification of hypoeutectic Al and Mg alloys
Journal name Acta Materialia  (ERA 2012 Listed)    (ERA 2010 Rank A*)   Check publisher's open access policy
Publication date 2010-01
Sub-type Article
Year available 2009
DOI 10.1016/j.actamat.2009.09.002
Volume number 58
Issue number 1
ISSN 1359-6454
1873-2453
Start page 261
End page 271
Total pages 11
Place of publication United Kingdom
Publisher Pergamon
Collection year 2010
Language eng
Subject C1
091207 Metals and Alloy Materials
861203 Metal Castings
Abstract Agglomeration and bending of equiaxed crystals were studied by microstructural characterization of specimens produced by near-static cooling, high-pressure die casting and Thixomolding®, where the solidifying crystals experience different levels of mechanical stresses. EBSD was used to acquire statistical grain misorientation data which is linked to crystal agglomeration and bending behavior during solidification. An aluminum alloy and two magnesium alloys were used to compare grain misorientations for different crystal structures. The length fraction of low-energy grain boundaries in HPDC and Thixomolded samples was substantially higher than in “statically cooled” samples. This is attributed to the high shear stresses and pressure applied on the solidifying alloy, which promote crystal collisions and agglomeration. In-grain misorientations were found to be significant only in branched dendritic crystals which were subjected to significant shear stresses. This is related to the increased bending moment acting on long, protruding dendrite arms compared to more compact crystal morphologies.
Keyword Solidification microstructure
Electron backscattering diffraction (EBSD)
Aluminum alloys
Grain boundary energy
Misorientation
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Received 11 August 2009; received in revised form 31 August 2009; accepted 2 September 2009 Available online 1 October 2009

 
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Created: Sun, 20 Dec 2009, 00:06:10 EST