Evaluation of microstructure stability at the interfaces of Al-6061 welds fabricated using ultrasonic additive manufacturing

Niyanth Sridharan*, Maxim N. Gussev, Chad M. Parish, Dieter Isheim, David N Seidman, Kurt A. Terrani, Sudarsanam S. Babu

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Ultrasonic additive manufacturing (UAM) is a solid-state additive manufacturing process that uses fundamental principles of ultrasonic welding and sequential layering of tapes to fabricate complex three-dimensional (3-D) components. One of the factors limiting the use of this technology is the poor tensile strength along the z-axis. Recent work has demonstrated the improvement of the z-axis properties after post-processing treatments. The abnormally high stability of the grains at the interface during post-weld heat treatments is, however, not yet well understood. In this work we use multiscale characterization to understand the stability of the grains during post-weld heat treatments. Aluminum alloy (6061) builds, fabricated using ultrasonic additive manufacturing, were post-weld heat treated at 180, 330 and 580 °C. The grains close to the tape interfaces are stable during post-weld heat treatments at high temperatures (i.e., 580 °C). This is in contrast to rapid grain growth that takes place in the bulk. Transmission electron microscopy and atom-probe tomography display a significant enrichment of oxygen and magnesium near the stable interfaces. Based on the detailed characterization, two mechanisms are proposed and evaluated: nonequilibrium nano-dispersed oxides impeding the grain growth due to grain boundary pinning, or grain boundary segregation of magnesium and oxygen reducing the grain boundary energy.

Original languageEnglish (US)
Pages (from-to)249-258
Number of pages10
JournalMaterials Characterization
Volume139
DOIs
StatePublished - May 1 2018

Fingerprint

3D printers
Welds
manufacturing
ultrasonics
Ultrasonics
microstructure
Microstructure
Grain boundaries
evaluation
Heat treatment
Grain growth
heat treatment
Tapes
grain boundaries
Magnesium
tapes
Ultrasonic welding
magnesium
Oxygen
ultrasonic welding

ASJC Scopus subject areas

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

Cite this

Sridharan, Niyanth ; Gussev, Maxim N. ; Parish, Chad M. ; Isheim, Dieter ; Seidman, David N ; Terrani, Kurt A. ; Babu, Sudarsanam S. / Evaluation of microstructure stability at the interfaces of Al-6061 welds fabricated using ultrasonic additive manufacturing. In: Materials Characterization. 2018 ; Vol. 139. pp. 249-258.
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Evaluation of microstructure stability at the interfaces of Al-6061 welds fabricated using ultrasonic additive manufacturing. / Sridharan, Niyanth; Gussev, Maxim N.; Parish, Chad M.; Isheim, Dieter; Seidman, David N; Terrani, Kurt A.; Babu, Sudarsanam S.

In: Materials Characterization, Vol. 139, 01.05.2018, p. 249-258.

Research output: Contribution to journalArticle

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