Crystallization characteristics of cast aluminum alloys during a unidirectional solidification process

Mitsuhiro Okayasu, Shuhei Takeuchi

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The crystal orientation characteristics of cast Al-Si, Al-Cu and Al-Mg alloys produced by a unidirectional solidification process are examined. Two distinct crystal orientation patterns are observed: uniform and random formation. A uniform crystal orientation is created by columnar growth of α-Al dendrites in the alloys with low proportions of alloying element, e.g., the Al-Si alloy (with Si 2% Cu or Mg), the uniform crystal orientations collapse in the Al-Cu and Al-Mg alloys, owing to interruption of the columnar α-Al dendrite growth as a result of different dynamics of the alloying atoms and the creation of a core for the eutectic phases. For the hypo-eutectic Al-Si alloys, a uniform crystal orientation is obtained. In contrast, a random orientation can be detected in the hyper-eutectic Al-Si alloy (15% Si), which results from interruption of the growth of the α-Al dendrites due to precipitation of primary Si particles. There is no clear effect of crystal formation on ultimate tensile strength (UTS), whereas crystal orientation does influence the material ductility, with the alloys with a uniform crystal orientation being elongated beyond their UTS points and with necking occurring in the test specimens. In contrast, the alloys with a nonuniform crystal orientation are not elongated beyond their UTS points.

Original languageEnglish
Pages (from-to)112-120
Number of pages9
JournalMaterials Science and Engineering A
Volume633
DOIs
Publication statusPublished - May 1 2015
Externally publishedYes

Fingerprint

cast alloys
Crystallization
Crystal orientation
aluminum alloys
solidification
Solidification
Aluminum alloys
crystallization
crystals
dendrites
eutectics
Eutectics
tensile strength
Tensile strength
interruption
alloying
Dendrites (metallography)
Alloying elements
ductility
Alloying

Keywords

  • Aluminum alloy
  • Lattice
  • Microstructure
  • Tensile property
  • Texture

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

Crystallization characteristics of cast aluminum alloys during a unidirectional solidification process. / Okayasu, Mitsuhiro; Takeuchi, Shuhei.

In: Materials Science and Engineering A, Vol. 633, 01.05.2015, p. 112-120.

Research output: Contribution to journalArticle

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